1 cup all-purpose flour
1 tablespoon sugar
1 teaspoon baking soda
1/2 teaspoon salt
1/2 cup sour cream
1/2 cup whole milk
1 large egg
2 tablespoons unsalted butter, melted, plus additional for cooking pancakes
Whisk together flour, sugar, baking soda, and salt in a bowl. Whisk together sour cream, milk, egg, and melted butter (2 tablespoons), then whisk into flour mixture.
Brush a nonstick skillet with melted butter and heat over medium heat until hot. Working in batches, pour 1/4 cup batter per pancake into skillet and cook until bubbles appear on surface and undersides are golden brown. Flip and cook other side, about 1 minute. Transfer to a baking sheet and keep warm in oven. Lightly butter skillet between batches.
Heat all ingredients in a small saucepan over medium-low heat, stirring occasionally, until butter has melted.