Step 1

Preheat oven to 200°. Melt ¼ cup butter in a small saucepan over medium heat and cook, stirring often, until butter foams, then browns (do not burn), 4–5 minutes. Let cool slightly.

Step 2

Meanwhile, purée buttermilk and oats in a blender until smooth. Add eggs, buckwheat flour, flaxseeds, sugar, baking powder, baking soda, and salt. Blend on high 30 seconds. Add butter and blend just to combine.

Step 3

Heat a large nonstick skillet over medium. Coat very lightly with butter. Working in batches, scoop about 3 tablespoonfuls of batter per pancake into skillet and cook until bottoms are golden brown and tops are evenly covered with bubbles, about 3 minutes. Turn and cook until cooked through and undersides are golden, about 2 minutes. Keep warm in oven and serve with plenty of syrup.

Step 4

Do Ahead: Pancakes can be made 2 weeks ahead; wrap in plastic and freeze.