Wash and slice the mushrooms thinly long ways.

In a large stovetop pan on medium-high heat, add the olive oil. Once the olive oil is hot, add the garlic and mushrooms. Cover the stovetop pan to allow the mushrooms to sweat out the moisture.

Cook the mushrooms for about 5 minutes covered. Once the mushrooms are tender, remove from the heat uncovered.

In a separate pan on medium-high heat, heat the milk. Be careful not to let it boil. Set aside.

In a small saucepan on medium-high heat, add the butter. Once the butter starts to change colors, add the flour and stir continuously for about 1 minute. Gradually add the warm milk stirring continuously. The sauce should be thickening as you stir. If you notice lumps, just keep whisking. See note 1 below

Add the parmesan cheese into the roux bechamel sauce and mix well. Pour the sauce over the mushrooms and mix.

Serve atop pasta or homemade sweet potato gnocchi.