There’s nothing more special than setting out a huge coffee cake for a Saturday breakfast or brunch. If you are pressed for time in the morning, you can prepare the batter, filling, and glazes a night or two beforehand. Pour the batter and filling into the pan and place the pan in the refrigerator. Then all you have to do in the morning is place the pan in the oven, then pour the glaze over the top after baking. Your house will be filled with the wonderful aroma of cinnamon and browned butter!
To make the cake batter, stir together the coconut flour, cinnamon, baking powder, and salt in a medium sized bowl; set aside. In a large bowl, using a hand mixer, beat the softened butter, sweetener, and vanilla until light and fluffy. Add the eggs one at a time, beating for at least 1 minute after each addition. Beat in the flour mixture alternately with the sour cream.
Pour half of the batter into the prepared pan. To make the cinnamon filling, place the sweetener, melted butter, cinnamon, and vanilla in a small bowl and stir well to combine. Pour the filling evenly over the batter in the pan, using a knife to swirl it into the batter. Pour the rest of the batter into the pan. Bake for 40 to 45 minutes, until a toothpick inserted in the center of the cake comes out clean.
Let it cool in the pan for 10 minutes, then turn it out onto a wire rack to cool completely. Meanwhile, make the browned butter glaze: Place the butter in a saucepan over medium-high heat and cook, whisking constantly, until brown (but not black!) flecks appear.
Keep heating and whisking; the butter will froth up and then settle down. Remove the pan from the heat. (If using coconut oil, simply heat the oil in the pan until melted.) Add the sweetener and whisk until smooth. Set in the refrigerator to cool for 5 to 8 minutes.