Instructions

• Preheat the oven to 350°F (175°C). Spray a 6‑mold donut pan with nonstick baking spray and set the pan aside.
• Make the crumb topping: in a small bowl combine 1/4 cup granulated sugar, 3 1/2 tablespoons all‑purpose flour, and 1/4 teaspoon cinnamon. Add 1/4 stick cold unsalted butter, cut into tiny cubes, and work the butter into the dry mixture with a pastry cutter, two forks, or your fingertips until the mixture resembles a coarse meal. Place the bowl in the freezer to chill while you make the batter.
• In a large bowl whisk together the dry donut ingredients: 1 cup all‑purpose flour, 1/2 cup light brown sugar (packed), 1/2 teaspoon salt, and 1 teaspoon baking powder.
• In a separate medium bowl whisk the wet donut ingredients: 1/2 cup full‑fat sour cream, 2 1/2 tablespoons unsalted butter (melted), and 1 large egg (at room temperature) until smooth and uniform.
• Pour or fold the wet mixture into the dry mixture and gently stir until just combined. Do not overmix; stop when there are no large streaks of flour.
• Fill the prepared donut pan: spoon or pipe the batter into the 6 molds, filling each mold to about three‑quarters full. Work quickly so the batter stays airy.
• Remove the chilled crumb topping from the freezer and evenly divide it over the tops of the filled donut molds.
• Bake in the preheated oven for 10–11 minutes, or until the donuts spring back when lightly pressed and are set in the center.
• Let the donuts cool in the pan for 10 minutes. After 10 minutes, gently lift the donuts out of the pan and transfer them to a wire rack to cool for a few more minutes.
• Make the vanilla glaze: in a small bowl whisk together 1/2 cup confectioners’ sugar, 1/2 tablespoon whole milk, and 1/2 teaspoon vanilla extract until smooth.
• Drizzle the glaze over the warm (but not piping hot) donuts and serve immediately.