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 soda, and a pinch of salt until evenly combined. This creates a light, airy base for your muffins.
In a separate bowl, mix the peanut butter and sugar using a whisk or spoon until the mixture is smooth, creamy, and fragrant, about 2 minutes.
Add the eggs one at a time to the peanut butter mixture, beating well after each addition until the mixture is glossy and slightly thickened.
Stir in the milk and vanilla extract until the batter becomes smooth and slightly runny, with a glossy appearance and a pleasant aroma.
Gently fold the dry ingredients into the wet mixture using a spatula or spoon, mixing just until no streaks of flour remain—be careful not to overmix, as this keeps the muffins tender.
Spoon or scoop the batter evenly into the prepared muffin tin, filling each cup about two-thirds full to allow room for rising.
Bake the muffins in the preheated oven for 18 to 20 minutes, or until the tops are golden brown and a toothpick inserted in the center comes out clean.
Remove the muffins from the oven and let them cool in the tin for about 5 minutes, then transfer to a wire rack to cool completely. The aroma of warm peanuts and baked goods will fill your kitchen.
Once cooled, enjoy these muffins warm or at room temperature. They taste great with a glass of milk or a spread of butter for extra indulgence.