Upside-Down Pear Gingerbread Cake!

I have a bunch of recipes backed up since I've been super lazy about cooking recently (and these are all from three or so weeks ago). Anyway, I made this cake when my mom was visiting in October. I wanted something special and autumnal, and this seemed fairly easy, which is important to me because I am not all that into baking. And it was delicious! Oh, and it's from this great cookbook by Jeanne Lemlin called Vegetarian Classics: 300 Essential and Easy Recipes for Every Meal. (Full title! Sometimes when I'm writing papers, I make sure to list the entire title to eat up space. Oh dear.)

Anyway, here it is!

Topping:
4 T. (1/2 stick) unsalted butter
1/2 c. firmly packed light or dark brown sugar
2 ripe but firm pears (Bosc or Anjou)

Cake:
1 c. unbleached flour
1 t. baking soda
1/4 t. salt
2 t. cinnamon
1 t. ground ginger
1/2 t. ground cloves
1 egg
1/2 c. firmly packed light or dark brown sugar
1/3 c. unsulfured molasses
1/2 c. sour milk (combine 1/2 c. milk with 1 T. vinegar and let sit for 5 minutes)
4 T. melted butter

To serve: whipped cream, spiked with rum! (This is especially good.)

1. Preheat over to 350 degrees and butter the sides of a 9-in. round cake pan (not a springform pan, apparently).
2. To make the topping, melt the butter in a small saucepan, add the brown sugar and stir together until blended. Scrape into cake pan and spread evenly.
3. Peel and slice each pear into quarters and get rid of the cores. Slice each quarter into 3 slices and then arrange 'em evenly around the pan (there should be 24).
4. To make cake: in a large bowl, combine the flour, baking soda, salt, cinnamon, ginger, and cloves. In a separate bowl, beat together the egg, brown sugar, molasses, sour milk, and melted butter. Add to flour mixture and stir until well-blended. (I tried not to overmix because I have heard that does something weird to cake batter.)
5. Pour the batter over the pears. Bake 30 minutes, or until a knife inserted in center comes out clean. Cook for 10 minutes or so and then invert on a plate (this is the fun part!). Serve with the whipped cream!