Start by browning 6 tbsp of butter low and slow until milk solids have turned golden brown. Watch this carefully because butter burns quickly. Pour into a small bowl and place in the fridge for 20-30 minutes or until it has turned back into a softer butter texture.
Start your dough! Place milk into a small bowl and microwave until it reaches 115 degrees (like warm bath water). Place milk into a large mixing bowl (or stand mixing bowl if you have it), and sprinkle yeast on top. Add sugar and let the yeast sit for a couple of minutes (about 3-5). Add melted butter, egg and egg yolk and mix on medium until combined.
Add in bread flour and salt and use a wooden spoon to mix well. Once mixed, either use your stand mixer with the hook or knead with hands for about 8 minutes. Dough shouldn’t be too sticky, if it feels sticky, add more bread flour 1 tbsp at a time. Sprinkle flour on your surface and knead.
Drizzle olive oil in a large bowl and form the dough into a ball and place into the bowl. Cover with a lid or plastic wrap and a towel and let rise for 1 hour.
While rising, make your filing with your cooled browned butter, add in brown sugar, cinnamon, and ground cardamom. Mix well into a paste. Set aside. Make your espresso glaze by mixing 2 shots of espresso, 2 cups powdered sugar, 1 tsp of vanilla, 1/4 tsp ground cardamom, and a pinch of salt. Mix well and set aside.
After one hour, use a rolling pin to roll out your dough into a 10x14 rectangle. Place your brown sugar mixture evenly on top of your dough. Sprinkle with a little more cinnamon and cardamom
Roll gently and tightly and try to seal the last bit at the end. Using a sharp serrated knife or a string of floss, cut your roll into 1" thick pieces and place 9 of them in a greased pan. I used a round cast iron for this. Cover and let rest again for 1 hour.
Pour 1/2 cup heavy cream in between the cinnamon rolls. Bake at 350 for 20-24 minutes (start with 20) and remove when golden brown. Let cool for 10 minutes and then glaze generously with espresso glaze!