Preheat the oven to 325F and line two baking sheets with silicone mats or parchment paper.
In a food processor, process the sliced almonds until they resemble oats.
In a large bowl, beat the peanut butter, butter, and sweeteners together on medium until light and fluffy, about 2 minutes. Beat in the egg and vanilla extract until well combined.
All at once, add the almond flour, processed almonds, baking powder, baking soda, and salt. Beat until combined.
Using about 1 tablespoon of dough at a time, roll into balls and place 2 inches apart on the prepared baking sheets. You should get about 32 cookies.
Bake 5 minutes, then press down firmly with a flat bottomed glass to about 1/3 inch thick. Bake another 15 minutes, switching and rotating the pans halfway through baking.
Remove from the oven. To create indentations on the top, gently press a meat mallet into the top of each cookie right after baking. You can also just leave them as is. Let cool completely on the pan - they will continue to crisp up as they cool.
Peanut Butter Filling
In a medium bowl, beat together the peanut butter and butter until smooth. Beat in the sweetener and vanilla until well combined.
If necessary, beat in a little cream to thin to a spreadable consistency (this will depend on your peanut butter).
Take 1 cookie and spread the bottom with about 1 to 1 1/2 tablespoons of filling and top with another cookie.