Preheat oven to 375 degrees. Line a baking sheet with parchment paper.Combine flour and baking powder in a bowl and set aside. Cream together butter and sugar until fluffy. Add the egg and vanilla and mix until combined. Gradually add dry ingredients and mix until the dough forms a ball. Turn out onto prepared baking sheet and press into a 12-inch circle roughly 1/4-inch thick. Bake 10-12 minutes, until cookie is golden around the edges. Cool completely.
Beat together cream cheese and sugar on high speed until fluffy. In a large bowl, whisk together the jam and lemon juice. Add the berries and toss to coat. Set aside for 15 minutes.To assemble, spread the cream cheese over the cookie crust and top with the berries.
You can substitute a 16 ounce tube of sugar cookie dough in lieu of making your own.