Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper. Ensure all ingredients are at room temperature before starting.
Mix the wet ingredients: In a large bowl, whisk together the butter, tahini, and allulose sweetener until smooth and homogenized. Add the egg and vanilla extract, then whisk again until fully incorporated.
Form the dough: Stir in the almond meal, baking powder, baking soda, salt, and chopped walnuts (if using). Mix with a spatula just until a sticky dough forms.
Chill: Gently fold in the chocolate chunks. Cover the bowl with cling film and refrigerate for 30 minutes.
Shape: Scoop the chilled dough using a tablespoon to make 12 equal portions. Roll each portion into a ball and place them on the prepared baking sheet. For a nicer look, press a few extra chocolate chips on top of each ball.
Bake and cool: Bake for 9 to 10 minutes, or until the edges are lightly golden brown. Remove from the oven and let the cookies cool completely on the baking sheet to firm up. Transfer to a serving plate and enjoy!