1. Cook your Meat (or saute mushrooms)

Heat a medium skillet over medium high heat and brown your beef or sausage until brown and cooked through. Drain, rinse off extra grease and set aside.

2. Make the White Sauce

Run a paper towel over your skillet to remove excess grease and return it to the stovetop and add the olive oil to the skillet over medium heat and heat until it shimmers, about 1 minute. Add the flour and whisk together until it starts to get light brown. Add salt and pepper.

Whisk in the milk, 1/2 cup at a time, allowing the sauce to heat back up and start to thicken. Continue adding and whisking until all the milk is gone. Turn off the heat and set the white sauce aside.

3. Assemble the lasagna

Heat your oven to 375°F

In a 13×9 pan or similar, add 1/2 cup marinara sauce to the bottom and lay one layer of noodles on the bottom (it’s okay to break a few to get them to fit). Spread 1/2 to 3/4 cup of white sauce on the noodles, top with 1/2 cup ground beef or sausage, and add 1/2 cup marinara sauce. Do this 2 more times for a total of 3 layers.

On top of the third layer, add one more layer of lasagna noodles and top with the shredded mozzarella cheese.

Tent the baking dish with foil and bake for 45 minutes. Take the foil off and continue to bake for another 15 minutes until the top is golden brown. Remove from the oven and let rest for 15 minutes before cutting.