Preheat oven to 325°F. Line a baking sheet with parchment paper. Allow 10 minutes for preheating. The oven should reach a steady 325°F with no fluctuations.

In a medium bowl, whisk together 2 cups almond flour, 1/2 cup unsweetened cocoa powder, 1/2 teaspoon baking soda, and 1/4 teaspoon sea salt. Whisk for 30 seconds until evenly combined and no cocoa clumps remain. Checkpoint: You should see a uniform brown mixture with no streaks of white from the almond flour.

In a separate large bowl, add 1/2 cup softened unsalted butter and 1/3 cup erythritol sweetener. Using an electric mixer on medium speed, beat together for 2–3 minutes until the mixture looks pale, fluffy, and increased in volume. It should resemble wet sand at first, then become creamy. Checkpoint: The mixture should have visible air bubbles and be noticeably lighter in color than before.

Add 1 large room-temperature egg to the butter mixture. Beat on medium speed for 1 minute until fully incorporated and no streaks of yellow remain.

Add 1 teaspoon vanilla extract to the mixture. Beat for another 30 seconds until combined.

Pour the dry ingredients into the wet ingredients. Using a spatula, fold gently until just combined—do not use the electric mixer at this step. Fold 10–15 times until no streaks of dry ingredients remain. Checkpoint: The dough should be thick and hold together when pinched, with no visible dry pockets of flour or cocoa.

Fold in 1/3 cup sugar-free dark chocolate chips and 1/4 cup chopped pecans or walnuts (if using). Fold 5 more times until evenly distributed. The dough is now ready to scoop.

Using a 1-tablespoon cookie scoop or rounded tablespoon, drop dough onto the prepared parchment-lined baking sheet. Space each scoop about 2 inches apart—cookies will spread slightly during baking. You should have 12–14 cookies.

Place the baking sheet on the middle rack of the preheated 325°F oven. Bake for 11–13 minutes. At 11 minutes, the edges should look set and slightly darker than the center, while the very center should still look soft and slightly underdone. At 13 minutes, cookies will be fully set but still fudgy inside. Checkpoint: Edges should be firm when gently pressed with a spatula; centers should give slightly. Cookies will harden as they cool.

Remove the baking sheet from the oven and place on a heat-safe counter or trivet. Allow cookies to rest on the hot baking sheet for 5 minutes. This firms up the structure without cooling them completely.

Using a thin spatula, transfer cookies to a wire cooling rack. They will continue to firm up as they cool. Allow 15–20 minutes of cooling before eating. The final texture will be chewy inside with slightly crispy edges.

Once completely cooled (about 20–30 minutes), store in an airtight container at room temperature for up to 5 days.