Preheat oven to 350°F. Line a large baking sheet with parchment paper and set aside.
In the bowl of an electric mixer, cream butter on low speed just until creamy, but not fluffy. Add the erythritol and mix again on low speed just until incorporated (again, not fluffy). Add almond flour on low speed and mix until crumbly.
Scrape down the sides of the bowl, and then form a cohesive ball of dough using your hands this time. Make sure to not knead the dough too much or to overmix it.
Next, roll out the dough to about 3/4-inch thickness on a flat surface between 2 sheets of parchment paper. It is important that the dough not be too thin, otherwise it will brown too much when baked. Let dough chill in the refrigerator on a lined baking sheet for 20-30 minutes, or until set. Cover with parchment paper before chilling.
Using a 2.5 to 3-inch diameter cookie cutter, cut into rounds or whatever shape you want to. Using a metal spatula, gently transfer keto cookies to the lined baking sheet and bake for 13-15 minutes, or until the bottom of the cookies changes color to a light brown. Transfer pan to a rack and let cookies cool before drizzling with or dipping in chocolate.
Once keto cookies are cool, melt chocolate chips in a medium microwave-safe bowl and heat for about 1-2 minutes, mixing until fully melted and smooth. If you wish, stir in 1/2 teaspoon of oil to keep the chocolate from re-solidifying quicker. Then either drizzle melted chocolate over the cookies using a fork, or dip the top of the cookies into the melted chocolate and let harden.