1.In A Large Saucepan, Saute Mushrooms In 1 Tablespoon Butter. Remove Mushrooms And Keep Warm. In The Same Pan, Cook Sausage Until No Longer Pink; Drain. Add Remaining Butter. Stir In Flour Until Blended. Gradually Add Milk, Salt And Pepper. Bring To A Boil; Cook And Stir For 2 Minutes Or Until Thickened And Bubbly. Remove From The Heat. Stir In Sour Cream And Mushrooms; Set Aside And Keep Warm. 2.In A Bowl, Beat Eggs, Milk, Salt And Pepper. In A Skillet, Melt Butter. Pour Egg Mixture Into Skillet. As Eggs Set, Lift Edges, Letting Uncooked Portion Flow Underneath. Cook Until Eggs Are Completely Set. Transfer To A Serving Plate. Spoon Sausage Mixture Over One Side Of The Omelet; Fold In Half.