Prepare the white sauce using a medium-sized saucepan on medium-high heat, add the block of cream cheese, milk, and garlic salt. Warm this up until it's fully melted and smooth. If sauce is too thick, add additional milk. It will be thicker than a marinara sauce, more spreadable.
Using a large skillet on medium-high heat, add in the olive oil and garlic clove, cooked chicken, and fresh spinach. Let this simmer for about 2 minutes until the spinach is wilted.
Spray a 9x13 baking dish with nonstick spray. Spread 1/3 of the white sauce on the bottom of the pan and place 3 noodles on top of the white sauce.
Add 1/3 of the chicken mixture, 1/3 of the cottage cheese, mozzarella cheese, and parmesan cheese. (Be sure to split each item into 3rds for 3 layers.)
Top with 3 more lasagna noodles and repeat.
On the last layer, add the 3 noodles, and then the remaining chicken mixture. Then, add 3 more noodles and top the noodles with the remaining sauce and cheese.
Cover the lasagna with aluminum foil.
Bake at 425°F covered with foil for 25 minutes. If any lasagna noodles are not fully covered with liquid or look uncooked, lightly press them down.
Carefully uncover and cook for an additional 5 minutes on LOW BROIL. This will crisp the top of the lasagna.
Let rest for 10 minutes before serving.
Notes
This can be made with regular lasagna noodles too if gluten-free is not a need, but remember to use oven-ready.