Preheat the oven to 180°C / 350°F. Grease a muffin tin and line with paper cases, or place silicone moulds on a baking tray.
Add the eggs, oil and vanilla to a blender and pulse briefly.
Add the roasted pumpkin, spices, milk, and sugar. Blend again until smooth.
Add the oats and baking powder, then blend once more just until combined. Do not overmix - the batter should remain slightly textured.
Divide the batter evenly between the muffin cups or moulds.
Bake for 20 minutes, or until a toothpick inserted into the centre comes out clean.
Allow the muffins to cool in the tin for 10 minutes, then transfer to a wire rack to cool completely.