First, finely chop or crush 1 cup of almonds. Then, prepare the pie crust mix according to the package directions. Divide the pastry in half, then divide each half into 5 parts. On a lightly floured surface, roll each part into a 5-inch circle. Use each circle to line a 3 1/2-inch fluted tart pan, pressing the pastry evenly into the bottom and sides; trim any excess. Refrigerate the lined tart pans for 30 minutes.
While the tart shells chill, preheat your oven to 375 degrees. In a bowl, cream the butter with the sugar on medium speed until the mixture is light and fluffy. Beat in the eggs, one at a time, until fully incorporated. Finally, stir in the finely chopped almonds, almond extract, and heavy cream until just combined. The filling will be ready to pour into the chilled shells.