Preheat your oven to 180°C (350°F). Grease your muffin tin or line it with paper liners and set aside.
In a large bowl, mix the creamy peanut butter and sugar together until smooth and slightly fluffy—this creates a fragrant, nutty base.
Add the large egg to the peanut butter mixture and whisk until well combined, feeling smooth and slightly frothy.
Pour in the milk and vanilla extract, stirring gently until everything is evenly incorporated. The batter should be thick but pourable.
In a separate bowl, whisk together the flour, baking powder, and salt to evenly distribute the leavening agents.
Gradually add the dry ingredients into the wet mixture, folding gently with a spatula or spoon just until combined—be careful not to overmix to keep the muffins tender.
Spoon the batter into the prepared muffin tin, filling each cup about three-quarters full. If desired, add a small dollop of peanut butter on top of each for extra gooeyness.
Bake in the preheated oven for 20-25 minutes, until the tops are golden and cracked slightly, with a fragrant peanut aroma filling your kitchen.
Remove the muffins from the oven and let them cool in the tin for about 5 minutes—this helps them set and makes removal easier.
Transfer the muffins to a wire rack to cool completely or enjoy them warm, appreciating their rustic cracked tops and moist crumb.
Serve these cozy muffins with a drizzle of honey or a sprinkle of coarse sea salt if desired, and enjoy their nostalgic peanutty aroma and satisfying texture.
