Preheat oven to 375 degrees F (190 C) and line two baking sheets with parchment paper. Set aside.
Add softened vegan butter to a large mixing bowl and beat until creamy and smooth - about 1 minute.
Add sugar and mix on medium speed until fluffy and light - about 1 minute. Then add vanilla and chickpea brine (or other egg substitutes*) and mix again, scraping down sides as needed.
Add peanut butter and mix once more. Then add baking powder and sea salt and blend to combine.
Lastly, add almond flour, cornstarch, and gluten=free flour blend and mix on low until the ingredients are combined.
The dough should be thick and almost difficult to mix at this point. If too soft, continue adding 1 Tbsp each gluten free flour blend, almond flour, and cornstarch until a thick, moldable dough is formed. If it is too dry for some reason, add 1 Tbsp (15 ml) almond milk and stir. Then transfer dough to the refrigerator and chill for 15 minutes*.
Use a cookie scooper (I like this one) or Tablespoon to measure out 1 1/2 Tbsp amounts of dough and gently roll into balls - the dough will still be soft, so be gentle. Arrange on the parchment-lined baking sheets and press down gently with the palm of your hand to smash slightly (see photo). The cookies won't spread much, so don't worry about giving them too much room on the baking sheet.
Bake for 11-12 minutes or until the cookies appear fluffy and the edges are slightly beginning to dry out. Remove from oven and immediately press an unwrapped peanut butter cup down in the center of the cookies. Don't press too hard or it can crack too much. Be gentle - they only need to be inserted enough to stick in place. Let cool on baking sheet for 10 minutes before transferring to a wire rack to cool completely (expedite cooling time by transferring to refrigerator).
Enjoy as is or with a glass of DIY Almond Milk or Hot Cocoa! Storage: Once cooled, store leftover cookies covered at room temperature for 3-4 days or in the freezer up to 1 month.
*If you’d like to cut back on sugar, sub 1/3 cup of the sugar with 1 packet (~3/4 tsp) stevia extract- I like Trader Joe’s brand (amounts as original recipe is written // adjust if altering batch size). This will make the cookies softer, so you may need to add more gluten free flour, almond flour, and/or cornstarch to help thicken the dough. *The chickpea brine substitutes an egg in this recipe. In its place, you can also try subbing 1/4 cup pumpkin puree, 1 egg replacer, or 1 small chicken egg if not vegan (amounts as original recipe is written // adjust if altering batch size). I haven’t tested it with a flax egg or any of the other substitutes and can’t guarantee the results. *If not gluten-free, you can try subbing the almond flour and gluten-free flour blend with unbleached all-purpose flour. *The almond flour in this recipe isn't replaced well by almond meal, so be sure to pick up flour! I included a link above. If you have a nut allergy, you can try subbing the almond flour with additional gluten free flour blend. *You can make the cookie dough ahead of time and refrigerate up to 2-3 days in advance. Simply let the dough rest at room temperature for 30 minutes before scooping and baking. It should be soft and moldable. *Nutrition information is a rough estimate for 1 of 18 cookies.