In a cast iron skillet add diced pears, butter, brown sugar, and cinnamon. Cook over medium heat until pears are soft and a slightly thickened syrup has formed. Remove from heat. Pears have a decent amount of liquid, so there will still be liquid left in the pan.
Remove 1 cup of cooked pears from pan.
In a large bowl combine the dry ingredients for the cake. Mix to combine. Then add in the wet ingredients, mixing to combine.
Add the cooked pears to the cake batter and fold the mixture together.
Pour the cake mixture back into the skillet and spread into an even layer.
Add the 1 cup of remaining pears to the top of the cake mixture. Spread over top, but do not mix in.
Bake for 35-40 minutes.
After the cake has been removed from the oven mix together the powdered sugar and heavy cream.
When the cake has slightly cooled, pour over the top of the cake and enjoy!
Notes
Don't skip cooking the pears first. This step is important! Raw pears release too much liquid in the cake and can make it soggy. Cooking them down first also deepens their flavor so much.
Leave the liquid in the pan. When you cook the pears, there will be syrupy liquid left in the skillet. That's actually going to help create a really flavorful base for your cake. Don't drain it!
Check your cake early. Every oven is a little different. Start checking at the 35-minute mark by inserting a toothpick into the center. It should come out with just a few moist crumbs.
Let it cool before icing. You want the cake slightly warm - not hot. If it's too hot, the icing will run right off. Give it about 10 minutes after pulling it from the oven.
Use a well-seasoned 11-12" cast iron skillet or enamel coated cast iron. This helps the cake release easily when you scoop it out and gives the edges a beautiful golden crust. If you don't have a large skillet swap for a 9x13 baking dish, this ensures that the cake cooks properly.