Preheat the oven to 350ºF and lightly grease a muffin tin or line with silicone liners.
Whisk the pumpkin puree, coconut sugar, milk, eggs, butter or oil, and maple syrup together in a large mixing bowl until smooth.
Add the flour, oats, baking powder, cinnamon, and salt and stir to incorporate into the wet ingredients. Fold in the diced apples.
Evenly distribute the batter among the 12 muffin molds, filling each until just below the top.
Bake until a toothpick comes out clean, 26 to 30 minutes.
Cool completely in the muffin tin before enjoying.
