Preheat oven to 350F. Butter and line with parchment paper a 9x5” loaf pan.

In a bowl, mix the flour, baking powder and salt together. Set aside.

In the bowl of a stand mixer fitted with the whisk attachment, combine the lemon zest and sugar. Rub together with your fingers to release the lemon essential oils.

Add the butter and mix until incorporated, then beat on HIGH speed for 4 minutes.

On Medium speed, add the eggs in one at a time.

On LOW speed, gradually pour in the buttermilk, vanilla, and lemon juice.

Add the flour mixture to mix just until combined. Use a rubber spatula to help finish folding in any remaining dry mixture to prevent over mixing.

Transfer half the batter to the loaf pan. Add dollops of half blueberry jam. Repeat with the remaining batter and blueberry jam.

Use a butter knife or skewers to swirl the batter together vertically, horizontally, then vertically once again.

Bake on the middle oven rack for 15 minutes.

Reduce heat to 325F to cook an additional 45 to 55 minutes, until center is set and a toothpick inserted into the center comes out clean.

Let cool in the pan for 20 minutes the remove to a wire rack to cool completely.

Slice the pound cake into ½” to ¾” thick slices. You’ll need an even amount, so slice into either 10 or 12 slices.

Add a very generous scooping of the gelato on to half of the slices, then sandwich the remaining slices on top.

Wrap tightly in either parchment paper or plastic wrap. Immediately store in the freezer to firm up for 4 to 8 hours. Remove from their wrapping to slice in half and serve.