Preheat your oven to 180°C (350°F) and line a muffin tin with paper liners or lightly grease it.
In a large mixing bowl, whisk together the flour, baking powder, and salt until evenly combined. This creates a light, airy mix that helps the muffins rise perfectly.
In a separate bowl, combine the peanut butter, sugar, and eggs. Whisk until the mixture is smooth, slightly thick, and fragrant with a nutty aroma.
Add the milk to the wet mixture and whisk again until all ingredients are well incorporated and the batter becomes smooth and slightly glossy.
Pour the wet ingredients into the bowl with the dry ingredients. Gently fold them together with a spoon or spatula until just combined—be careful not to overmix, as this keeps the muffins tender and light.
Spoon the batter into the prepared muffin tin, filling each cup about 3/4 full. If desired, sprinkle chopped peanuts or chocolate chips on top for added texture and flavor.
Bake in the preheated oven for 18-20 minutes, or until the muffins are golden on top and a toothpick inserted into the center comes out clean.
Remove the muffins from the oven and let them cool in the tin for about 5 minutes, which helps them set and makes handling easier.
Transfer the muffins to a wire rack and allow them to cool completely. The smell of roasted peanuts and baked bread will fill your kitchen, and the muffins will develop a soft, moist crumb with gooey pockets of peanut butter.
Once cooled, enjoy these warm or at room temperature, perhaps with a smear of butter or a drizzle of honey for extra richness.