Preheat oven to 325F/ 165C. If necessary, grease all 12 cups of your muffin tin with (vegan)butter, (coconut/olive) oil or non-stick cooking spray or line each one of them with a paper muffin cup.
In a large bowl, beat the oil and maple syrup together with a whisk. Add the (flex)eggs, and beat well. Add the pumpkin purée, oat milk, pumpkin spice blend, baking soda, apple cider vinegar vanilla extract and salt.
Add the flour and oats to the bowl and mix with a large (wooden) spoon, just until combined (a few lumps are ok). Fold in any add-ins now (or just sprinkle them on top like I do in this recipe).
Divide the batter evenly between the muffin cups. Sprinkle the tops of the muffins with about a tablespoon of oats/craisins/pumpkin seeds.
Bake muffins in the preheated oven for 24 to 26 minutes, or until a toothpick inserted into a muffin comes out clean.
Place the muffin tin on a cooling rack to cool. These muffins are delicate until they cool down. You might need to run a butter knife along the outer edge of the muffins to loosen them from the pan if you are not using muffin tin liners.
The muffins keep at room temperature for up to a day, or in the refrigerator for up to 4 days. In the freezer in a freezer-safe bag they will keep for up to 3 months (just defrost individual muffins as needed and warm up (highly recommended).