Preheat your oven to 350°F (175°C).
Line an 8×8 inch baking pan with parchment paper, leaving some overhang on the sides for easy removal.
In a large mixing bowl, combine 1 cup creamy peanut butter and 1 cup granulated sugar. Stir until smooth and well combined.
Add 1 large egg and 1 teaspoon vanilla extract to the peanut butter mixture. Mix thoroughly until the batter is smooth.
Add 1/2 teaspoon baking soda and 1/4 teaspoon salt to the batter. Stir until fully incorporated.
Spread the batter evenly into the prepared baking pan, smoothing the top with a spatula.
Bake in the preheated oven for 18 to 20 minutes, or until the edges are set and the top is lightly golden.
Remove from the oven and allow the cookie bars to cool completely in the pan on a wire rack.
Once cooled, use the parchment paper overhang to lift the bars out of the pan and cut into 16 squares.
Serve and enjoy your gluten free peanut butter cookie bars!