Pesto White Sauce Chicken Lasagna 

3 tablespoons butter
3 tablespoons olive oil
1 small onion chopped (about 1 cup)
3 cloves garlic minced
2 teaspoons dried basil or 1 tablespoon fresh
1/2 teaspoon salt
1/4 teaspoon pepper
6 tablespoons flour
2/3 cup yogurt
1 & 2/3 cup broth
2 cup cooked chicken, chopped (rotisserie is best)
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15-24 ounces ricotta or cottage cheese
1/3 cup basil pesto
1 egg
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9 lasagna noodles or other pasta
1.5 cups mozzarella cheese
2-3 cups fresh spinach
3-4 tablespoons Parmesan cheese

Make white sauce:
Saute onion and garlic in butter and oil (add other chopped veggies if not using spinach)
Add chicken and cook until just done
Add basil, salt, pepper
Add flour and stir until moistened
Combine yogurt and chicken broth; add slowly to the pan, stirring constantly. 
Cook over medium heat, stirring, until the mixture is thickened slightly. 

Make cheese mix:
Combine ricotta, pesto, and egg.

Assemble lasagna:
Put thin layer of white sauce on bottom of pot
Make three layers:
- Pasta: 3 lasagna noodles (break into pieces as needed to fill pan area) or an equivalent amount of other pasta (if making in slow cooker, you don't need to precook the pasta)
- Ricotta mixture
- Spinach, if using
- White sauce
- Mozzarella 
Repeat twice
Sprinkle the top with Parmesan cheese

Slow cook for 4 hours ("normal" in Instant Pot; "low" in Crock Pot) or bake in oven if using precooked pasta (about 45 minutes at 350, covered).