Butterscotch Bars

8 Tablespoons (1 stick) unsalted butter
1 1/4 cups packed light brown sugar
2 large eggs
1/2 teaspoon pure vanilla extract
1 cup unbleached flour
1/4 teaspoon salt
1 teaspoon baking powder
1/2 cup butterscotch chips
1/3 cup semisweet chocolate chips

Grease a 9 x 9-inch baking pan with butter. Dust with flour and tap out the excess. Preheat the oven to 350 degrees.

Melt the butter in a small saucepan over low heat. Set aside to cool.

Cream the sugar, eggs, and vanilla in a medium bowl until smooth. Add the cooled butter and continue mixing until well blended.

Measure the flour, salt and baking powder and then sift together directly into the batter. Mix the batter gently until well combined and no trace of the dry ingredients remains. Stir in the butterscotch and semisweet chips.

Spread the batter in the prepared baking pan and bake for 20 minutes or until a toothpick inserted in the center comes out clean or with only crumbs, not batter, sticking to it.

Remove from the oven and cool on a rack for 1 hour. Cut just before serving.

Makes 12 to 16 bars