Preheat oven to 350°F (175°C). Grease or line an 8×8-inch baking pan with parchment.
In a bowl, whisk melted butter and brown sugar. Add egg, honey, and vanilla; whisk until combined.
Stir in flour, salt, and ½ teaspoon cinnamon until just combined.
Pour batter into pan. Mix granulated sugar and remaining ½ teaspoon cinnamon and sprinkle over batter.
Bake 22–25 minutes until a toothpick inserted in center comes out clean. Cool completely before cutting.
