Preheat the oven to 350 F. Line a 12 cup muffin pan with paper liners. In a large bowl, whisk together flour, granulated sugar, cocoa powder, salt, and baking powder. Add in eggs, melted butter, and vanilla extract and mix until smooth.
Evenly divide the brownie batter between the prepared muffin pan. Top with strawberry jelly and swirl with a knife. Bake for 15-20 minutes.