In a medium bowl, whisk together the flour, cocoa powder, baking powder, and a pinch of salt until evenly combined.
In a separate bowl, whisk the honey, milk (or almond milk), and melted coconut oil until smooth.
Fold the dry ingredients into the wet ingredients and mix until a smooth batter forms. Stir in the dark chocolate chips.
In a small bowl, combine the almond butter and coconut sugar until well mixed to make the filling.
Divide half of the chocolate batter among four microwave-safe mugs (about a spoonful each), then add about 1 tablespoon of the almond butter mixture into the center of each mug.
Top each with the remaining batter so the filling is covered, then sprinkle slivered almonds evenly over the tops.
Cover each mug with a paper towel and microwave on high for 1 minute. Check doneness and microwave an additional 10–20 seconds if needed; avoid overcooking.
Let the mug cakes cool for a few minutes before serving.