If you don't have buttermilk, mix the milk and vinegar in a measuring cup and set aside for 5 minutes.
Mix the whole wheat flour (1/2 cup), oats (1/2 cup), baking powder (1 teaspoon), baking soda (1/2 teaspoon), kosher salt (1/4 teaspoon), and brown sugar (2 tablespoons) in a medium bowl.
Mix the buttermilk (or milk and vinegar mixture) with the egg and beat well.
Add egg mixture to dry ingredients, stirring until just combined (do not overwork the batter!).
Fold 1 cup of berries into the batter gently.
Heat a cast iron skillet or other heavy skillet / griddle and cook pancakes in melted butter in 1/3 cup amounts over medium heat. Flip when slightly browned around edges and bubbles form at the top.
Serve with extra berries and drizzle with maple syrup.
If you want to use honey instead of brown sugar, add 2 tablespoons of honey to the milk mixture when you add the egg. Pour into the dry ingredients.
Want to use frozen berries? They will work fine! Just thaw ahead of time, and know that your pancakes will be purple/blue/red from the juices from the berries :-)
The provided nutrition information does not include any added sodium from seasoning to taste, any optional ingredients, and it does not take brands into account. Feel free to calculate it yourself using this calculator or by adding the recipe to Yummly.