Black Sesame-Pear Tea Cake

Preheat oven to 325 °F. Butter one 9x5x3" loaf pan or six 4x2x2" paper or metal loaf pans. Whisk 1 1/2 cups flour, next 4 ingredients, and 2 tablespoons sesame seeds in a medium bowl. Grind remaining 1/2 cup sesame seeds in spice mill to form a thick paste, about 2 minutes. Using an electric mixer, beat 1/2 cup butter and 1 1/3 cups sugar in a large bowl until well combined, 2-3 minutes. Add sesame paste and beat, occasionally scraping down sides of bowl, until blended, 1-2 minutes. Add egg and egg yolk. Beat until pale and fluffy, 3-4 minutes. On low speed, beat in flour mixture in 3 additions, alternating with buttermilk in 2 additions, beginning and ending with dry ingredients. Toss pear with remaining 2 tablespoons flour in a small bowl; fold into batter. Spoon batter into prepared pan; smooth top. Sprinkle with remaining 2 tablespoons sugar. Bake until a tester comes out clean when inserted into center, about 1 hour 40 minutes for large loaf and 45-55 minutes for small loaves. Let cool in pans on a wire rack.