Preheat oven to 350°. Grease a 13-by 9-inch baking pan.
Combine 1/2 cup of the butter and 1/2 cup granulated sugar in the bowl of an electric mixer. Beat until fluffy. Add 2 cups flour, the baking powder and 1/2 teaspoon salt. Beat until crumbly. Transfer crumbs to the baking pan and pat down. Bake 10 minutes.
Beat cream cheese, remaining 1/4 cup granulated sugar, lemon zest and juice and almond extract until fluffy. Add eggs, beat well after each addition.
Pour cream cheese mixture evenly over the crumb crust and bake 20 minutes until the cheesecake has set.
In a medium bowl, stir together the brown sugar, remaining 3/4 cup flour, cinnamon and ¼ teaspoon salt. Add remaining 6 tablespoons butter, cut into 1/2-inch pieces and stir until mixture is crumbly. Stir in almonds.
Sprinkle blueberries and crumb mixture over cheesecake and bake 20 minutes until the crumbs have browned. Cool and refrigerate at least 2 hours until the cheesecake is firm before cutting into 24 bars.
