Preheat the oven to 350°F.

To prepare the pears, cut the pears into 1/8 to 1/4-inch slices. Melt the butter in a 10-inch cast iron skillet over medium heat. Add the brown sugar and salt and cook until melted, stirring occasionally. Remove from the heat, add the vanilla and stir to combine.

Decoratively place the pear slices onto the caramel, overlapping them as you do, and starting with a circle of pears in the center, fanning them out as you go. Though, really, however you place them will be both pretty and delish.

To make the cake, add the flour, cocoa powder, sugar, baking powder, baking soda and salt to a large mixing bowl and whisk to combine.

Combine the milk, oil, egg, yolk and vanilla in large glass measuring cup and whisk to combine. Pour over the dry ingredients and fold with a flexible spatula until smooth.

Add the espresso powder and boiling water to the measuring cup, no need to wash it, whisk until incorporated and pour the mixture into the mixing bowl, whisking a final time.

Pour the batter over the pears in the prepared pan and bake for 25 to 30 minutes, rotating at the halfway point. The cake is ready when a toothpick inserted in the middle comes out with a moist crumb or two.

Immediately run a paring knife around the edge of the skillet. Let sit for 5 minutes, then carefully invert the cake onto a serving platter.

Let cool until the caramel sets a bit, about 20 minutes, or cool to room temperature. Serve with vanilla ice cream or whipped cream.