filet mignon with madeira sauce with beef

3 tablespoons butter 2 tablespoons olive oil 3/4 lb sliced mushrooms 1/2 chopped onion 2 cloves chopped garlic 1 teaspoon thyme salt and pepper 4 filet mignon[...]

3 tablespoons butter 2 tablespoons olive oil 12 ounces button mushrooms , thinly sliced 1/2 cup minced shallot (about 3) 4 garlic cloves , minced 1 tablespoon[...]

5 tablespoons butter , divided 2 tablespoons oil, divided 1 lb white button mushrooms , thinly sliced (can use less) 1/2 cup minced shallot , divided (about 3[...]