Heat oven to 350 degrees F. Coat a 15 x 10 x 1-inch pan with nonstick cooking spray.
Beat together the butter and sugar until smooth, about 2 minutes. Add eggs, one at a time, beating well after each. Beat in almond extract. On low speed, beat in flour and salt until just blended. Spread evenly into prepared pan.
Fan apple slices over top, then brush with preserves. Bake at 350 degrees F for 25 minutes.
Whisk together the flour, brown sugar, pumpkin pie spice and salt. Stir in the butter until mixture is moistened and clumps together. Sprinkle evenly over cake. Bake for an additional 35 minutes. Remove pan to wire rack; cool completely.
Dust with confectioners sugar and cut into 24 squares.