In a medium bowl, place oats and hot water. Stir and set aside.
Place all remaining dry ingredients into a large bowl. Stir to combine. Form a well in the center and crack eggs into the well while beating them lightly with a spoon. Add milk and stir batter well with large spoon until well combined.
Pour melted butter into hot oat mixture; stir. Pour hot oats into batter and stir again until well combined. Cover and refrigerate at least overnight.
To make 4 muffins muffins: 1 cup of muffin mix makes approximately 4 muffins. To every cup, add about ½ cup of mix ins such as berries, grated carrot, chocolate chips, nuts, or dried fruit.
To make only one muffin, use ¼ cup batter and approximately 2 tablespoons mix ins.
Bake in greased muffin tin or a muffin tin lined with cupcake papers at 400 for 20 minutes, or until lightly browned.