Start by measuring your sugar and setting it aside. In a separate bowl, simply whisk together the flour, baking powder, and salt until they're well blended.
In your mixer, combine the softened butter and sugar. Beat them on medium speed for about 2-3 minutes until the mixture looks light and fluffy. Scrape down the sides of the bowl, then add the vanilla extract and egg, mixing until everything is smoothly incorporated.
Gradually add the dry flour mixture to the wet ingredients on a low speed until just combined. Finally, gently mix in the mini chocolate chips until they're evenly distributed throughout the dough. Good news: this dough doesn't need to chill, so you can start baking right away!
Preheat your oven to 350°F (175°C). Lightly flour your work surface or a pastry mat. Roll out part of your cookie dough to about 3/16 inch thick. Use a larger heart-shaped cookie cutter (around 2.5 inches) to cut out 12 full heart shapes and place them on a parchment-lined baking sheet. Then, take a smaller heart-shaped cutter (about 1.25 inches) and cut out the centers of 6 of the remaining hearts; these will be your "top" cookies.
Bake your heart cookies for a quick 6-7 minutes. Keep a close eye on them, as they bake fast and should remain light in color. Once out of the oven, let them rest on the baking sheet for 2-3 minutes before carefully transferring them to a wire rack to cool completely.
Once the cookies are totally cool, spoon about a teaspoon of strawberry jelly onto each of the solid heart cookies. Carefully place a cutout heart cookie on top of each jelly-filled one, pressing lightly. The jelly will help "glue" the two cookie halves together, creating a beautiful, sweet treat!