Position racks in the top and bottom thirds of the oven; preheat to 500°. Divide the squash and onions between two large rimmed baking sheets. Add 3 tbsp. oil and 1/2 tsp. crushed red pepper to each sheet and toss; season with salt. Roast until tender, about 30 minutes total. Halfway through cooking, rotate the sheets, switch them between racks and stir the vegetables.
Meanwhile, in a large bowl, toss the kale, garlic, the remaining 2 tbsp. oil and a pinch of salt. Remove the vegetables from the oven. Immediately divide the kale between the baking sheets; toss until the kale wilts slightly. Let the sheets stand on wire racks until the vegetables cool, about 45 minutes.
Divide the squash-kale mixture among five 1-gallon freezer bags. Squeeze out the air.
And...Freeze: Stack the bags flat and freeze up to 3 months. When you’re ready to cook, scoop out the amount of vegetables needed for your recipe. If the vegetables clump together, rap the bag on the counter to break apart. To thaw, place vegetables in the fridge overnight, or microwave on defrost until thawed, 4 to 5 minutes.