Saute garlic, onion, zucchini, and red pepper until onions are translucent. Add salt, pepper, and basil. Stir to combine. Set aside.
Cover the bottom of cooker with marinara sauce and a layer of noodles, broken to fit.
Divide half of the vegetable mixture, followed by half of the spinach leaves and half of the cheese for layers. Pour half of remaining sauce on top.
Repeat layers again and top with remaining lasagna noodles. Then add pesto and remaining cheese.
Put the lid on the slow cooker and cook on high setting for 3-4 hours or on low setting for 7-8 hours. Turn off the slow cooker and sprinkle the reserved mozzarella on the lasagna. Cover and let stand for 10 minutes to melt the cheese.
Let cool and serve.

1 1/2 teaspoons garlic cloves, minced
1 cup red onion, diced
2 cup zucchini, diced
3/4 cup red bell pepper, diced
3/4 teaspoon black pepper
1 tablespoon fresh basil, chopped
15 (12 oz) whole-wheat lasagna noodles, uncooked
1 cup marinara sauce
1/2 cup spinach
1 bag of Beyond Meat beef flavor
1 cup dairy free mozzarella shreds
1/4 cup pesto