Line 2 regular-sized muffin pans with 36 liners.
Mix together all the filling ingredients. It should be firm enough to roll into balls.
1 1/4 cups (320 grams) natural peanut butter, 1.5 ounces (43 grams) xylitol, 1.125 ounces (31 grams) erythritol, 3/16 teaspoon powdered stevia, 1 teaspoon vanilla extract, 1/4 teaspoon salt, 1/4 cup (32 grams) coconut flour
Melt the chocolate and coconut oil in a small pot or microwave in a microwave-safe bowl.
4 cups (740 grams) keto semi-sweet chocolate, 1/4 cup (56 grams) coconut oil
Pour 1.5 teaspoons (8 grams) chocolate per cup on the bottom. Place in the freezer. It'll only take about 10 minutes for them to freeze.
Meanwhile, roll the peanut butter layer into eighteen 2-teaspoon (11-gram) balls. Flatten and place over the frozen chocolate layer. Don't make the balls so big that they go to the edges - you want the chocolate layer on top to completely cover the top of the peanut butter layer + the edges so that the chocolate layers come together.
Place in the freezer another 10 minutes. Once ready, rewarm the chocolate, if necessary (if it's thickened a little, it'll be more difficult to handle), and then add 2 teaspoons (11 grams) chocolate on top of the peanut butter layer.
Freeze until hardened. Then you can remove the liners. Keep in the fridge for a few weeks or in the freezer for several months. Can also sit at room temperature for about a week.