Preheat the oven to 350 F (177 C). Lightly grease and line the bottom and two sides of a 9 x 9 inch (23 cm) or 9 x 13 cake pan with parchment paper. Alternatively, grease the pan really well and omit the parchment paper.
In a small bowl whisk the light brown sugar and cinnamon together until well combined. Set aside for now.
¾ cup (150 g) light brown sugar, 1 tablespoon ground cinnamon
In a medium bowl whisk the all purpose flour, baking powder, baking soda and salt together until well combined. Set aside for now.
2 cups (240 g) all purpose flour, 1 teaspoon baking powder, 1 teaspoon baking soda, ½ teaspoon salt
In a large mixing bowl, cream the butter and sugar together until light and fluffy. This takes about 2-3 minutes on medium speed. On low, mix in the eggs and vanilla extract until smooth and well combined. Alternating dry ingredients and buttermilk, mix in ⅓ of the dry ingredients into the wet, followed by ½ of the buttermilk. Repeat with until all the ingredients are just combined. 1 cup (226 g) unsalted butter, room temperature, 1½ cup (300 g) granulated sugar, 3 large eggs, room temperature, 2 teaspoons (10 ml) vanilla extract , 1 cup (240 ml) buttermilk, room temperature
Evenly spread half of the honey cake batter into the prepared pan. Top the cake layer with the ½ of the cinnamon sugar. Repeat with the remaining cake batter. Top with the remaining cinnamon sugar. Swirl the sugar into the cake batter.
Bake the honey bun cake for 40 - 50 minutes or until a toothpick inserted into the center of the cake comes out clean or with a few moist crumbs. Cool the pan in the pan for 15-20 minutes. Once the cake has cooled a bit, take a toothpick and poke lots of holes all over the top of the cake. Make the honey glaze by whisking powdered sugar with melted butter, honey and milk or heavy cream. Top the honey cake with the glaze, allow about 30 minutes for the glaze to set.
1½ cups (180 g) powdered sugar, 2 tablespoons (30 ml) melted butter, 1 tablespoon honey, 2 - 3 tablespoons milk, room temperature