In a large bowl, add the dry ingredients and whisk to blend.
In a microwave-safe dish, melt the butter. Add the peanut butter and the hot butter will soften the peanut butter. Add the eggs and vanilla. *If your melted butter mixture is too hot, you will need to temper the eggs so they don't cook in the hot butter. To do this, whisk your eggs in a dish. Add 1 tablespoon of the hot mixture and whisk constantly. Repeat 2-3 times. Pour into the rest of the wet ingredients and mix.
Pour the wet ingredients into the dry ingredients, add the mix-ins, and mix well.
Use a cookie scoop to drop peanut butter cookie dough balls onto a parchment paper-lined cookie sheet.
Take a fork and press each cookie dough ball down with the fork. I do this in a plus shape in two directions as shown in the photos.
Bake for 10 minutes. Remove from the oven to a cooling rack.
I have tested this recipe with King Arthur Measure for Measure GF and Bob's Red Mill 1 to 1 GF blend. That doesn't mean others will not work, I just have not tested other flours. If the brand you use is high starch, you may need to use less flour.
If your gluten free flour blend doesn’t contain xanthan gum or guar gum, please add 1 teaspoon.
To make this recipe dairy-free, substitute the butter for vegan butter.
To make this recipe nut-free, use SunButter spread instead of peanut butter.
I recommend using no salt added peanut butter.
These cookies will keep up to 4 days in an air-tight container, or up to 4 months in the freezer.