Preheat oven to 350ºF (180ºC).
Grease with soft butter, shortening or baking spray and line the pan you’ll be using with parchment paper. Round pans don’t need to be lined, but, if using the 8x11-inch pan, I like to line it with a strip of parchment paper covering the bottom and two long sides; the short sides will remain unlined but greased. This makes removing the block of cake easier after it’s baked.
Sift flour, baking powder, baking soda and salt. I have them measured and sift them directly into the batter, but you can sift them separately in a medium bowl if that’s more convenient for you.
In a large bowl beat the soft butter and sour cream until smooth and no lumps remain.
Gradually add both sugars while beating at medium/high speed for 3 minutes, until light in color and the sugar is partially dissolved.
Add eggs, one at a time, beating well after each addition. The batter might look curdled but it will be fine after the dry ingredients are added.
Add the vanilla extract and mix.
Sift the flour mixture (flour, baking powder, baking soda and salt) and add it in 2 parts together with the spices. I have them measured and sift them directly into the batter, but you can sift them separately if that’s more convenient for you.
Mix well at low speed, but don’t over beat at this point or the cake will be tough after it’s baked.
Pour batter into the prepared pan and smooth the top.
Add the pear slices on top of the cake, creating a pattern or however you want them placed.
Sprinkle with cinnamon sugar if using.
Bake for about 50-55 minutes for the 10-inch round or rectangular cakes, and 60-70 minutes for the 9-inch cake, until the top is golden and a cake tester or toothpick inserted comes out clean.
Important: if the top is browning too quickly, cover it with a piece of aluminum foil after 40-45 minutes of baking. This will prevent it from darkening further but the cake will still continue to bake. Start checking for doneness at the lowest time specified in this recipe and have patience until it’s fully baked. It might take a little more (than the highest time specified) depending on your oven, especially for round cakes.
Let cool on a wire rack and remove from the pan. If you lined the pan, make sure the unlined sides are not sticking to the pan and then lift the paper carefully so the cake is also easily lifted with it.
Dust with powdered sugar if you want before eating.
It keeps well for a day or two at room temperature, covered in plastic wrap or under a cake dome. After that refrigerate or freeze, always well wrapped.