Preheat the oven to 350°F. Line a rimmed baking sheet with parchment paper.
Heat the oil in a large skillet over medium-high heat. Add the beef and onion and cook, stirring to break down the beef into small pieces, until the beef is no longer red, for about 4 minutes. Drain.
Return the drained beef mixture to the skillet. Add the garlic, salt, pepper, cumin, and smoked paprika. Cook, stirring, for 1 more minute. Remove from the heat and set aside.
To make the fathead dough, place the mozzarella in a medium microwave-safe bowl. Place the cubed cream cheese on top. Microwave for 30 seconds. Stir with a rubber spatula, then microwave for 30 more seconds. Stir again, then mix in the almond flour as best as you can - the dough won't come together yet. Add the egg and mix well with the spatula, then use your hands to work the batter into a smooth, elastic, slightly sticky dough.
Place the dough between two parchment sheets and roll it to ⅛-inch thickness. Cut as many 3.5-inch circles as you can using a cookie cutter or a wine glass. Re-roll the scraps and cut more circles. You should be able to get about 12 circles.
Place the dough circles on the prepared baking sheet. Place a heaping tablespoon of the beef mixture on one half of each circle, leaving a ½-inch border, then fold the dough over to make a half-circle and pinch the edges closed.Alternatively, Place a heaping tablespoon of the beef mixture on one circle, top it with another circle, and pinch the edges closed. This will naturally create fewer empanadas.
Bake the empanadas for 10 minutes. Carefully turn them over and bake them for 8-10 minutes longer, until golden brown. Cool for 10 minutes before serving.
Video
Notes
Traditionally, the edges are crimped with a fork to make a pretty pattern. But I find that the keto dough is a bit too sticky for that, so I skip this step.
You can use ground pork instead of ground beef in the filling. Ground chicken or ground turkey are also an option, but make sure you use ground dark meat and not white meat, which is too dry.
Empanadas are best when freshly baked. But you can keep the leftovers in the fridge, in an airtight container, for up to 4 days. Reheat them gently, covered, in the microwave at 50% power. You can also freeze them for up to 3 months.