In a large bowl, whisk together the dry ingredients: 1 cup oat flour, 1 cup white whole wheat flour, 2 1/4 teaspoons baking powder, 1/2 teaspoon baking soda, and 1/4 teaspoon salt.

If you want toppings, set aside a small portion of the banana (slice it) and a small portion of the blueberries now. In a separate bowl, combine the wet ingredients: slightly beaten 2 eggs, 1/4 cup canola oil, 1 mashed banana (use the remainder after reserving slices), 2 tablespoons honey, 1 cup buttermilk, and 1/2 cup low-fat milk. Whisk until mostly smooth.

Pour the wet mixture into the dry ingredients and stir gently until just combined; small lumps are okay—do not overmix.

Fold in 1/2 cup fresh blueberries and, if using, 1/2 cup diced walnuts (optional).

Preheat a griddle or large nonstick skillet to 350°F (or medium–medium-high). Test heat by dropping a few drops of water on the surface; they should sizzle. Lightly grease the griddle or spray with nonstick cooking spray.

Pour about 1/4 cup batter per pancake onto the hot griddle. Cook until bubbles form on the surface and the edges look set and the bottoms are golden, about 2–3 minutes. Flip and cook the other side until golden and the pancake is cooked through, about 1–2 minutes more.

Transfer cooked pancakes to a plate and keep warm while you finish the remaining batter. Serve topped with the reserved banana slices and reserved blueberries, if desired.