Preheat your oven to 350 degrees Fahrenheit. This is an essential step; getting the oven warm enough ensures that your cupcakes will rise properly as they bake.
In a medium-sized bowl, whisk together the all-purpose flour, baking powder, and kosher salt. This helps to evenly distribute the leavening agent, ensuring that your cupcakes rise beautifully.
In a separate bowl, combine the peanut butter, egg, and sugar. Whisk these together until they become creamy and well-blended, making sure there are no lumps.
Now, slowly whisk in the milk into the peanut butter mixture until it's fully incorporated, giving you a smooth and creamy batter.
Take the wet ingredients and gently fold them into the dry ingredients. Stir just until combined; be careful not to overmix, or your cupcakes might turn out dense.
Grease or line a standard 12-cup muffin tin with cupcake liners. Fill each cup about two-thirds full with the batter to allow space for rising.
Place the muffin tin in the preheated oven and bake for 20 to 25 minutes. Check for doneness by inserting a toothpick into the center of a cupcake; it should come out clean.
Once baked, remove the cupcakes from the oven and let them cool in the pan for about 10 minutes before transferring them to a wire rack to cool completely.
While the cupcakes cool, prepare your frosting. In a bowl, combine all frosting ingredients and whisk until smooth and creamy.
Spread the cream cheese frosting on top of each cooled cupcake. You can get creative and add a dollop of jelly on each for a fruity twist.
Serve the cupcakes to your eager guests or enjoy them yourself. These Breakfast Cupcakes are best enjoyed fresh, but they can be stored for later!