. Preheat the oven to 400º.
Line a standard 12-cup muffin tin with cupcake liners or use a spray.
In a medium bowl beat together the eggs, milk, and oil. Set aside.
In a small bowl, mix together the flour, oatmeal, sugar, baking powder, and salt. Gently stir this into the egg mixture until just combined. To have light, fluffy muffins, do not overmix the batter.
If you are adding fruit to the batter, coat the fruit first with 1 tablespoon flour and then gently fold the fruit into the batter so the fruit will not sink to the bottom of the muffins. Or add fruit to each muffin cup.
Spoon the batter into the muffin tins, filling them about 2/3 of the way up.
Bake at 400º for 8 minutes, then lower the oven temperature to 350º and bake for another 5-8 minutes or until a cake tester inserted in the center comes out clean.
Cool the muffins in the tin on a wire rack for 5 minutes, then carefully remove them from the tin and place them on the wire rack to continue cooling.
Store the muffins covered at room temperature.