Mix softened butter and peanut butter until smooth, then add brown sugar and salt and mix well.

Add egg and vanilla extract, mixing thoroughly. If using a manual whisk, beat the egg separately and add gradually.

Sift all-purpose flour and baking soda into the mixture and mix until no dry flour is visible.

Refrigerate the dough for 30 minutes.

Divide the dough into 45g portions and shape into flat rounds.

Bake in a preheated oven at 180°C for 8 minutes.

Immediately after removing from the oven, insert 2 pretzels into each cookie, then bake for an additional 2 minutes at 180°C.