M&M Bars

Preheat the oven to 350 degrees. Line an 8 inch square metal pan with nonstick foil or parchment.Sift or just stir together the flour, baking powder and salt.

Combine the butter and shortening in a mixing bowl and beat with a handheld mixer until creamy. Scrape sides of the bowl.

Add both sugars; beat on low, then on medium speed for about until light and fluffy.In a second bowl, mix together the eggs, vanilla and sour cream. With mixer on low or by hand, gradually add the egg mixture to batter in three parts.Stir in the flour mixture, followed by the M&Ms.

Transfer the dough to the pan, patting it in evenly and smoothing the surface.

Bake for 22 minutes uncovered (at which point it should brown, but a little jiggly in the center), then lay a sheet of foil loosely over the top and with a sheet of foil and bake for about 4 more minutes or until middle no longer jiggles.Cool for 1 hour at room temperature, then transfer to the refrigerator and finish cooling in the refrigerator. Lift from pan, set on a cutting board, cut into 16 squares.