Preheat the oven to 200 degrees . In a bowl, whisk the first 3 ingredients with 1/8 tsp. salt. Add 1 tbsp. maple syrup and 1/2 tbsp. butter. Combine with a fork until a crumbled mixture forms.
In a large bowl, whisk the buttermilk, egg and vanilla. Whisk in flour mixture. Let stand 5 minutes; fold in berries.
In a large nonstick skillet or griddle, melt 1 tsp. butter over medium heat. Add two 1/3-cup scoops of batter to the skillet, spacing about 2 inches apart. Cook until browned on the bottom and bubbles begin to pop on top, about 3 minutes. Flip and cook until browned and cooked through, about 2 minutes. Transfer to a heatproof platter; place in the oven to keep warm. Repeat with 3 more tsp. butter and batter.
Heat the remaining 1/2 tbsp. butter in another large nonstick skillet over medium. Add the remaining 2 tbsp. maple syrup, 1/8 tsp. salt and the bananas. Cook, stirring often, until heated through, 2 to 3 minutes. Spoon over pancakes.