Preheat oven to 375 degrees Fahrenheit.

Grease a muffin tin.

In a large bowl, whisk together the flour, baking powder, and cinnamon. Set aside.

Put the melted butter and lentils in a food processor or blender. Puree until smooth.

Add the egg, milk, vanilla extract, and pumpkin puree to the blender. Mix until combined.

Pour the wet ingredients into the dry and stir just until mixed.

Divide the batter among 12 muffin cups, filling each about 2/3 full.

Bake in the preheated oven for 18-20 minutes or until an inserted toothpick comes out clean.

Cool in pan for 5 minutes.

Remove from pan and cool completely on wire racks.