1Heat oven to 325°F. Grease bottom and sides of 13x9-inch pan with shortening or cooking spray; lightly flour. In small bowl, dissolve 1 teaspoon espresso in 2 teaspoons hot water. Add butter and 3/4 cup sugar; beat with electric mixer on medium speed until fluffy. On low speed, beat in 1 1/4 cups flour until blended. Press in pan.
2Sprinkle 1/2 cup of the toffee bits evenly over crust; press in slightly. Bake 15 to 17 minutes or until edges are light golden brown.
3In medium bowl, dissolve 1 tablespoon espresso in 1 tablespoon hot water. Add milk, 1 cup sugar and the eggs with electric mixer on medium speed until well blended. Stir in 2 tablespoons flour, the baking powder and salt. Pour over hot crust; spread evenly.
4Bake 28 to 33 minutes or until set. Immediately sprinkle with remaining 1/4 cup toffee bits. Cool completely in pan on cooling rack, about 1 hour. For bars, cut into 8 rows by 4 rows.