Preheat oven to 375°F. Line a 24-cup mini muffin pan with liners and spray with non-stick cooking spray.
In a large bowl, whisk together the flour, sugar, baking powder and salt.
In a medium bowl, whisk together the milk, eggs, peanut butter, and yogurt until smooth. Add the wet ingredients to the dry ingredients and stir until well combined.
Scoop 1 teaspoon of batter into each prepared muffin cup. Top with 1/2 teaspoon jelly and then another 1 teaspoon of muffin batter. Using a toothpick, swirl 1/4 teaspoon of jelly into the top of the batter of each muffin.
Bake for about 20 minutes or until the muffins have risen and a toothpick inserted in the center comes out batter-free. Let cool in pan 10 minutes before transferring to a wire rack to cool completely. Store in an airtight container.