Coffee Cake Muffins

INGREDIENTS

• 1/2 cup (1 stick) unsalted butter, room temperature, plus more for pans
• 1 3/4 cups all-purpose flour (spooned and leveled), plus more for pans
• 2 teaspoons baking powder
• 1 teaspoon baking soda
• 1 cup sour cream
• 1 cup granulated sugar
• 1 teaspoon pure vanilla extract
• 2 large eggs
• Confectioners' sugar (optional)
• 1 cup packed dark-brown sugar
• 1 cup all-purpose flour, (spooned and leveled)
• 1/2 teaspoon salt
• 1/2 teaspoon ground cinnamon
• 1/2 cup (1 stick) chilled unsalted butter, cut into small pieces