Preheat Oven: Preheat your oven to 350°F (175°C). Line a muffin tin with silicone or parchment liners, or lightly grease it if needed.
Mix Dry Ingredients: In a large bowl, combine the rolled oats, ground flaxseeds, cinnamon, ginger, nutmeg, cloves, baking powder, and salt. Stir well to evenly distribute the ingredients.
Mix Wet Ingredients: In another bowl, whisk together the pumpkin puree, plant-based milk, applesauce, maple syrup, and vanilla extract until smooth and well combined.
Combine Wet and Dry: Pour the wet ingredients into the bowl of dry ingredients. Stir until everything is evenly mixed. If using, fold in the chopped nuts and chocolate chips, dried cranberries or raisins.
Fill the Muffin Tin: Divide the oatmeal mixture evenly among the muffin cups, filling each one to the top. Add toppings if you like.
Bake: Bake in the preheated oven for 25-30 minutes, or until the tops are golden brown and a toothpick inserted into the center comes out clean.
Cool and Serve: Allow the oatmeal cups to cool in the pan for a few minutes before transferring them to a wire rack to cool completely. Enjoy warm or at room temperature.