Preheat your oven to 180°C (350°F) and line your muffin tin with paper liners or grease it well.
In a large mixing bowl, combine the peanut butter and sugar, stirring until the mixture is smooth, creamy, and fragrant. You should see a glossy, slightly thick batter.
Add the eggs one at a time, mixing well after each addition. The batter will become smoother and slightly thicker, with a rich aroma of roasted peanuts.
Stir in the vanilla extract until evenly incorporated, enhancing the aroma and sweetness of the batter.
In a separate bowl, whisk together the flour, baking powder, and salt to ensure even distribution of leavening and seasoning.
Gradually fold the dry ingredients into the wet mixture, just until combined. Be gentle to keep the batter light and airy—avoid overmixing for tender muffins.
Scoop the batter evenly into the prepared muffin tin, filling each cup about two-thirds full. The batter will be thick but scoopable, with a nutty aroma lingering in the air.
Bake in the preheated oven for 15-20 minutes, or until the tops turn golden brown and a toothpick inserted into the center comes out clean. You’ll hear a gentle bubbling sound as the muffins rise and set.
Once baked, remove the muffins from the oven and let them cool in the tin for about 5 minutes. Then transfer them to a wire rack to cool completely, which helps prevent sogginess and allows the flavors to develop.
Enjoy these muffins warm or at room temperature. They have a soft, tender crumb with a rich peanut aroma and slightly chewy texture from the oats or nuts if added.