Meal-Prep Friendly Sweet Potato & Beet Casserole with Wilted Spinach

I created this jewel-toned casserole on a frantic Sunday night when my fridge was bursting with farmers-market beets and the last of a baby-spinach clamshell. The goal? A make-ahead lunch that wouldn’t taste like “health food” by Wednesday. One bite of the roasted-sweet-potato topping against the earthy beet layer and I was hooked; by Friday my co-workers were begging for the recipe. It’s since become my signature bring-to-new-parents dish, my pot-luck ace in the hole, and the thing I crave when the weather turns crisp. The colors alone feel like a celebration, but it’s the slow-caramelized onions and garlicky spinach that make you close your eyes and sigh. Completely vegetarian, naturally gluten-free, and happy to sit in the fridge for five days without getting soggy—this is meal-prep that feels like Sunday supper every single day.

Ingredient Breakdown

Sweet potatoes bring the creamy, caramelized lid that bubbles and browns like a marshmallow-topped casserole—without the sugar crash. Choose orange-fleshed varieties like Garnet or Beauregard for maximum beta-carotene and that classic Thanksgiving vibe. Beets are the stealth star; roasted until their edges concentrate into jammy pockets, they add iron, folate, and a shocking magenta hue that stains the beans a playful pink. Speaking of beans, a humble can of cannellini or great Northern beans disappears between layers, pureeing slightly to create a silky “sauce” that keeps the casserole from drying out while sneaking in extra protein for Meatless Monday. Spinach wilts in a flash of garlic and olive oil, shrinking from a mountain into a verdant ribbon that cuts the sweetness with grassy notes. Finally, a trio of aromatics—onion, garlic, and thyme—roast alongside the vegetables so their sugars melt into the olive oil, becoming an instant dressing once scraped off the pan. Together they taste like you spent hours stirring a stove, when really the oven did all the heavy lifting.

Step-by-Step Instructions

1. 1

   Heat the oven & prep the sheet pan

   Preheat to 425 °F (220 °C). Line a rimmed baking sheet with parchment for easy cleanup. In a small bowl whisk 3 Tbsp olive oil, 1 tsp kosher salt, ½ tsp black pepper, and 1 tsp dried thyme. You’ll brush this on everything.

2. 2

   Roast the beets & onions

   Peel 3 medium beets (about 1 lb) and cut into ½-inch cubes. Thinly slice 1 large red onion. Spread both on half the sheet pan; drizzle with half the seasoned oil; toss to coat. Roast 15 min while you prep sweet potatoes.

3. 3

   Add sweet potatoes to the party

   Peel 2 large sweet potatoes and slice into ¼-inch coins. Push beet mixture to one side; lay sweet potatoes on the other half; brush with remaining oil. Roast 20 min more until all vegetables are tender and edges caramelize.

4. 4

   Wilt the spinach

   Heat 1 Tbsp olive oil in a large skillet over medium. Add 2 minced garlic cloves; cook 30 s until fragrant. Pile in 5 oz baby spinach; season with pinch salt. Toss until just wilted, 2–3 min. Squeeze in juice of ½ lemon to brighten.

5. 5

   Layer the casserole

   Reduce oven to 375 °F (190 °C). Lightly oil a 9-inch square or 2-qt baking dish. Spoon roasted beets & onions evenly into bottom. Scatter 1 can rinsed white beans over beets. Top with wilted spinach. Finish with overlapping sweet-potato coins.

6. 6

   Season & cover

   Brush sweet-potato tops with any remaining oil from the sheet pan. Sprinkle ½ cup crumbled feta (or nutritional yeast for vegan) and 2 Tbsp pepitas for crunch. Cover tightly with foil.

7. 7

   Bake & brown

   Bake 20 min covered to meld flavors. Remove foil; bake 10 min more until feta softens and sweet potatoes’ edges crisp. Broil 1–2 min for golden spots. Cool 10 min before slicing into 6 squares.

Expert Tips & Tricks

• Wear gloves when handling beets to avoid magenta fingers for days.
• Slice sweet potatoes uniformly with a mandoline so they cook at the same rate and fan like fish scales.
• Save the beet greens: Sauté with garlic for tomorrow’s side dish—zero waste, extra nutrients.
• Pepitas = crunch without nuts, keeping this lunchbox-friendly for nut-free offices.
• Make-ahead hack: Roast vegetables on Sunday; assemble and bake Monday night—tastes fresh.
• Reheat slices in a dry skillet instead of the microwave to resurrect crispy edges.

Common Mistakes & Troubleshooting

Variations & Substitutions

• Vegan: Skip feta; whisk 3 Tbsp tahini with lemon juice & drizzle over top for creaminess.
• Goat cheese swirl: Dot 4 oz soft chèvre instead of feta for tangy pockets.
• Spicy Moroccan: Add 1 tsp harissa to the oil and sub cilantro for thyme.
• Low-carb: Replace sweet potatoes with par-cooked cauliflower slices.
• Green swap: Use kale or chard instead of spinach; just massage with oil first.
• Bean swap: Chickpeas or black beans work; they’ll change color but taste great.

Storage & Freezing

Cool the casserole completely, then slice into six squares. Slide each into a glass meal-prep container or wrap in compostable parchment plus foil. Refrigerate up to 5 days; flavors deepen by Day 2. For freezer mode, flash-freeze squares on a tray 1 hour, then transfer to a zip-top bag; exclude as much air as possible and freeze up to 3 months. Thaw overnight in the fridge, then reheat in a 350 °F oven 15 min or microwave 2 min with a splash of water to re-steam.

Frequently Asked Questions

Pack a square into your lunchbox, drizzle with a little balsamic reduction, and watch your midday slump disappear in a blaze of purple-orange glory. Happy prepping!

Sweet Potato & Beet Casserole with Spinach

4.7

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A vibrant, make-ahead main dish packed with roasted vegetables, greens, and plant-based protein—perfect for weekly meal prep.

Prep

20 min

Cook

45 min

Total

1 h 5 m

Serves 6

Easy

Ingredients

• 2 medium sweet potatoes, peeled & cubed
• 3 medium beets, peeled & cubed
• 4 cups fresh spinach
• 1 can (15 oz) chickpeas, drained
• 1 small red onion, sliced
• 3 cloves garlic, minced
• 2 tbsp olive oil
• 1 tsp smoked paprika
• ½ tsp dried thyme
• ½ tsp sea salt
• ¼ tsp black pepper
• ¾ cup vegetable broth
• ⅓ cup tahini
• Juice of ½ lemon
• 2 tbsp pumpkin seeds (optional topping)

Instructions

1. 1
   Preheat oven to 400 °F (200 °C). Toss sweet potatoes and beets with 1 tbsp olive oil, salt, pepper, paprika, and thyme on a parchment-lined sheet. Roast 25 min until just tender.
2. 2
   While vegetables roast, heat remaining oil in a skillet over medium heat. Sauté onion 3 min; add garlic and spinach, cooking until wilted, about 2 min. Season lightly.
3. 3
   Whisk tahini, lemon juice, and vegetable broth until smooth to create the creamy base.
4. 4
   Lower oven to 375 °F (190 °C). Lightly oil a 2-qt baking dish. Layer roasted vegetables, chickpeas, and sautéed spinach mixture.
5. 5
   Pour tahini sauce evenly over the top; sprinkle with pumpkin seeds if using.
6. 6
   Cover with foil and bake 20 min. Remove foil and bake 10 min more until edges bubble and top is lightly golden. Cool 10 min before serving or portioning for meal prep.

Recipe Notes

• Stores up to 5 days refrigerated or 3 months frozen.
• Reheat single portions in microwave 2-3 min or oven 15 min at 350 °F.
• Swap spinach for kale or add crumbled feta for extra flavor.

Calories

285

Protein

10 g

Carbs

38 g

Fat

11 g