====== Ingredients - Topping ======
  * 6 tablespoons unsalted butter 
  * 3/4 cup packed dark brown sugar
  * 1 teaspoon ground ginger 
  * 1 teaspoon ground cardamom 
  * 1 teaspoon ground cinnamon 
  * 2 ripe Bosc pears (1 lb. total) 

====== Ingredients - Cake ======

  * 1 1/2 cups all-purpose flour
  * 2 teaspoons baking powder
  * 2 teaspoons ground ginger
  * 1 1/2 teaspoons ground cinnamon
  * 1/2 teaspoon ground cardamom
  * 1/4 teaspoon ground allspice
  * 1/4 teaspoon ground cloves
  * 1/4 teaspoon kosher salt
  * 6 tablespoons unsalted butter, softened
  * 3/4 cup packed light brown sugar
  * 2 large eggs
  * 1/2 cup whole milk
  * 2 tablespoons molasses or sorghum syrup
  * 1 teaspoon vanilla extract

====== Procedure ======

  - Prepare the Topping: Cook butter in a 10-inch cast-iron skillet over medium until butter is lightly browned and has a nutty and toasted aroma, about 5 minutes. Remove from heat. Immediately add brown sugar, ginger, cardamom, and cinnamon, and stir until smooth.
  - Peel, halve, and core pears. Cut the halves from top to bottom into 1⁄4-inch-thick slices, and press gently to fan the slices. Carefully -place pears on Topping in skillet. (Don’t pack them in—you might have a few left over.) Set skillet aside.
  - Prepare the Cake: Preheat oven to 350°F. Whisk together flour, baking powder, ginger, cinnamon, cardamom, allspice, cloves, and salt in a medium bowl.
  - Beat butter and brown sugar in a large bowl with mixer on high speed until light and fluffy, about 2 minutes, stopping to scrape down sides of bowl. Add eggs, 1 at a time, beating well after each addition.
  - Add half of flour mixture to butter mixture; beat on medium speed until smooth, about 2 minutes. Add milk, molasses, and vanilla, and beat until smooth, about 3 minutes. Add remaining flour mixture; beat 2 minutes, stopping twice to scrape down sides of bowl. Pour batter over Topping and pears in skillet, and gently spread to edges.
  - Bake in preheated oven until Cake is golden brown and springs back when touched lightly in center, 30 to 40 minutes. Cool in skillet on a wire rack 5 minutes.
  - Carefully invert warm Cake onto a serving platter. (Some pear slices might stick to the skillet; gently loosen and replace on cake.) Cool completely, about 45 minutes.