Preheat the oven to 350°F (175°C). Line an 8" x 8" baking pan with parchment paper, leaving an overhang on two sides to lift the bars out easily.

In a stand mixer or a mixing bowl with an electric hand mixer, beat 1 stick (1/2 cup) softened (not melted) unsalted butter or ghee until fluffy, about 1–2 minutes.

Add 1/3 cup sugar-free sweetener and 1 tsp pure vanilla extract. Beat until creamy and combined, scraping the sides of the bowl with a rubber spatula as needed.

Add 1 large room-temperature egg and beat until fully incorporated.

Add 1 1/2 cups super fine almond flour, 1/2 tsp baking soda, 1/2 tsp sea salt, and 1/2 tsp ground cinnamon (optional). Mix on low speed or fold with a spatula until the dough is evenly combined and no dry streaks remain.

Stir in 1 cup sugar-free chocolate chips until they are evenly distributed through the dough.

Transfer the dough to the prepared 8" x 8" pan and press it into an even layer, smoothing the top with a spatula. If desired, sprinkle a few extra chocolate chips on top.

Bake on the center rack at 350°F. Baking time depends on desired texture: - For gooier, under-baked bars: 18–20 minutes. - For slightly soft, set bars: 20–25 minutes. - For firmer bars: 25–30 minutes. The bars are done when the edges are golden brown and the center appears set (not wet). Optionally, you can bake 20 minutes, then turn off the oven and let the pan sit in the closed oven for 5 minutes for a slightly softer finish.

Remove the pan from the oven and cool on a wire rack. Allow the bars to cool at least 40 minutes (until mostly set) before using the parchment overhang to lift them from the pan and slice.