Preheat your oven to 350°F. Grease a 9-inch round cake pan and line the bottom with parchment paper—trust me on this, it makes removing the cake so much easier. Whisk together your flour, baking powder, and salt in a separate bowl, then set aside.

Cream together softened butter and sugar for about 3 minutes until it looks light and fluffy. You'll see it pale slightly, which means air's getting incorporated (that's what makes your cake tender). Add the eggs one at a time, beating well after each addition.

Stir in the vanilla bean paste and lemon zest into the wet mixture. The zest adds this bright pop that makes people ask what your secret is. Mix for about 30 seconds until everything's combined and fragrant.

Alternate adding the flour mixture and milk to your butter mixture, starting and ending with flour. Mix on low speed after each addition—don't overmix or you'll toughen the batter. Begin with 1/3 of flour, then half the milk, then another 1/3 flour, remaining milk, and finish with the last flour portion.

Fold in the white chocolate chips and fresh blueberries gently with a spatula. Pour half the batter into your prepared pan, then dollop spoonfuls of strawberry jam over the top. Add the remaining batter and swirl it slightly with a knife (don't overdo it).

Bake for 35 to 38 minutes until a toothpick inserted in the center comes out mostly clean with just a few crumbs. The cake should smell amazing at this point. Don't panic if it looks slightly underbaked—it firms up as it cools.

Let your 4th of july homemade cake cool in the pan for 15 minutes, then turn it out onto a wire rack. Cool completely before adding any frosting or glaze (about 2 hours). This patience step keeps everything from sliding around and looking messy.