Preheat your air fryer to 300°F.
Add butter, brown sugar, and granulated sugar to a large mixing bowl. Cream the ingredients on high for 2-3 minutes until smooth.
Add the peanut butter and mix well. The mixture should be smooth and creamy. Add the egg and the vanilla extract and incorporate them well.
Sift the flour, baking powder, and salt and add it to the mixing bowl. Stir slowly until the dough is mixed together. Mix just enough to form a cookie dough, but not too much.
Use a #60 or #70 cookie scoop (1 tablespoon) to form balls of cookie dough. Dump the other ½ cup of granulated sugar into a shallow bowl or a plate and place the cookie dough balls in the sugar. Roll them around until the cookies are coated in sugar.
Place the cookie dough balls onto your work surface. Use a glass to press the cookies flat to about ¼-inch thick. Or you can use a fork to press them flat. Transfer the cookies to your air fryer, spacing them out. You can fit about 9 in most large air fryers.
Cook the cookies in batches in the air fryer at 300°F for 8 minutes. If you like crispy cookies, cook them for 10 minutes. If you are using the air fryer setting on your large oven, see the notes below for correct instructions.
Remove the cookies from the air fryer and allow them to cool on a wire rack.