Preheat oven to 350 degree F. Lightly coat a 13x9x2-inch baking pan with nonstick cooking spray; set aside.
In a large bowl stir together the flour, ground almonds, 1/3 cup sugar, baking powder, and salt. Using a pastry blender cut in butter until mixture resembles coarse crumbs. Beat egg yolks slightly; add to dry mixture and toss with a fork until moistened (mixture will be crumbly). Pat dough into prepared pan. Bake for 20 minutes.
Meanwhile, in a medium mixing bowl beat the cream cheese and 1/3 cup sugar with an electric mixer on medium speed until fluffy. Beat in egg whites and almond extract just until combined. Spread cream cheese mixture over partially baked crust. Arrange apricot slices in even rows on top of cream cheese mixture to cover. Bake for 30 minutes more.
Finely snip any large pieces of apricots in preserves. In a small saucepan, cook and stir preserves over low heat until melted. Brush over warm bars. Cool completely in pan on a wire rack. Cut into squares. If desired, serve with whipped cream. Store in an airtight container in the refrigerator for up to 3 days. Makes 20 squares.