Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a large bowl, beat 0.5 cup unsalted butter and 0.75 cup erythritol on medium speed for 2–3 minutes until light and fluffy.
Add 1 large egg and 1 teaspoon vanilla extract; continue beating until just combined.
In a separate bowl, whisk together 1.5 cups all-purpose flour, 0.5 teaspoon baking soda, and 0.25 teaspoon salt.
Gradually add the dry ingredients to the butter mixture on low speed, mixing until just combined.
Fold in 1 cup sugar-free chocolate chips with a spatula.
Drop rounded tablespoons of dough onto the prepared sheet, spacing cookies about 2 inches apart.
Bake for 10–12 minutes, or until edges are lightly golden and centers are set.
Let cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.