Preheat oven to 350 degrees Fahrenheit. Lightly grease the sides and bottom of a 9x9 square baking pan and line with parchment paper. Set aside.
In a medium bowl, combine the flour, baking soda, cinnamon, nutmeg, salt, and cloves. Whisk until well blended.
In the bowl of a stand mixer fitted with the paddle attachment, beat butter, sugar, and vanilla on medium speed until well blended, about 3 minutes.
Add the eggs, one at a time, beating well after each addition. Scrape the bowl and beaters periodically, as needed.
Add about half of the flour mixture and mix on low speed until just blended.
Add the sour cream and continue mixing just until blended.
Toss the pears into the remaining flour mixture, coating them evenly, then, using a silicone spatula, fold it into the batter.