Combine flour, sugar, baking powder, and salt in a large bowl.
Mix milk, eggs, peanut butter, peanut oil, and vanilla extract together in a separate bowl. Pour into the flour mixture; stir batter until smooth.
Heat a nonstick griddle or skillet over medium-high heat. Drop about 1/4 cup batter onto the griddle. Sprinkle a few bacon pieces on top. Cook until bubbles form and the edges are dry, 3 to 4 minutes. Flip and cook until browned on the other side, 2 to 3 minutes. Repeat with remaining batter.