Preheat the oven to 325 degrees F. Grease a 9 X 3 inch round cake pan.: The warm, dry breath of the oven helps the cake rise properly, and a 9 X 3 inch pan creates the right depth so the pear slices can sit in the caramel without sinking. When your oven reaches 325 degrees F you will notice a steady, gentle heat rather than a blast that could brown the top too quickly. I always wipe the pan with softened butter or use a thin coat of neutral oil to prevent sticking. A common misstep at this stage is forgetting to grease thoroughly at the edges which can cause the cake to cling when inverted, so be meticulous about coating every part of the pan.
Spread the brown sugar out evenly on the bottom of the cake pan and spread out the butter pieces on top of the sugar. Place the pan in the oven for 8 minutes. Remove the pan and stir the butter/sugar mixture until combined and smooth. Spread it out evenly on the bottom of the pan. Lay the pear wedges on top of the butter/sugar mixture in spoke/circular fashion.: As the dark brown sugar and butter warm, they melt into a bubbling, caramel like pool that perfumes the air with molasses notes and a rich toasted sugar aroma. Stirring after the short oven time ensures the mixture is uniform and glossy, creating an even bed for the pear wedges. Arrange the fruit so slices overlap slightly in a spoke pattern, creating a pretty visual once inverted. Watch for hot spots while in the oven, and use an oven mitt when stirring, the pan will be hot. A typical error here is letting the sugar burn, which gives a bitter edge, so keep the oven step to about 8 minutes and stir promptly.
In a large mixing bowl, combine the flour, sugar, baking soda, baking powder, salt, cinnamon, nutmeg, and ground ginger. Add the eggs, oil and milk and beat just until combined. Add the fresh grated ginger and beat just until combined. Pour the batter evenly over the pears in the pan. Bake in an oven preheated to 325 degrees F for 1 hour or until a toothpick inserted into the middle of the cake comes out clean. Remove the cake from the oven and let it cool in the pan for 20 minutes before inverting it onto a cake platter.: When you whisk dry whole wheat flour with spices, you release a warm, fragrant dust that hints at the finished cake. Adding eggs , oil , and buttermilk creates a batter that should be smooth but not overworked; the batter will smell faintly of spice and fresh ginger . Pouring the batter gently over the arranged pears helps keep the fruit in place. As the cake bakes at 325 degrees F , you will notice an even rise and a golden hue around the edges; the aroma of spice will deepen and fill the kitchen. Insert a toothpick into the center to check for doneness, if crumbs cling, it needs more time. Letting the cake rest for 20 minutes allows the caramel to set slightly so the top releases cleanly when inverted. A common problem is removing the cake too soon which causes it to stick, so patience here is rewarded.
To make the caramel sauce: Place all sauce ingredients in a saucepan and bring to a boil. Once the butter is completely melted, let the sauce simmer for another 3 minutes. Remove from heat and stir in the vanilla extract. Spread about 2 tablespoons of the caramel sauce evenly over the warm cake (on top of the pear wedges). Serve the cake with the remaining caramel sauce and some whipped cream if desired.: Place all sauce ingredients in a saucepan and bring to a boil. Once the butter is completely melted, let the sauce simmer for another 3 minutes. Remove from heat and stir in the vanilla extract. Spread about 2 tablespoons of the caramel sauce evenly over the warm cake (on top of the pear wedges). Serve the cake with the remaining caramel sauce and some whipped cream if desired. : As the sauce comes to a boil, the sugars dissolve and the mixture thickens to a glossy, syrupy consistency, while the scent of melting butter and caramelized sugar becomes richer. Simmering for about 3 minutes concentrates flavors and gives the sauce body without graininess. When you stir in the vanilla extract , a sweet floral aroma blossoms and balances the caramel’s depth. Spoon a modest amount over the warm cake so the fruit gleams, then reserve the rest for drizzling at the table. Watch the heat and stir frequently to prevent scorching, since burnt spots will darken the flavor. A frequent mistake is boiling too long which can make the sauce too thick when cooled, so keep an attentive eye.