Work with the Bartlett pears at 68 to 72°F because cold fruit tightens the batter later. Peel and core both pears. Dice one and a half pears into 1/4-inch cubes and cut the remaining half into exactly 12 thin wedges. Finish the cutting within 6 to 8 minutes. Then toss the cubes with 1 tablespoon flour and 1 teaspoon cinnamon using quick lifting motions. The cubes should look lightly dusted and separate rather than wet or clumped. You’ll smell cinnamon before pear juice starts pooling. Keep the 12 wedges in one loose layer. Wait longer than 10 minutes and the cubes release liquid, which can streak the batter and sink the fruit. Coat quickly because flour traps surface juice and protects the crumb.

Heat the oven to 375°F and keep the dairy and eggs near 70°F. Whisk 2 cups flour with baking powder, baking soda, salt, 1 teaspoon cinnamon and nutmeg for 30 seconds. In another bowl whisk brown sugar, melted butter, eggs, Greek yogurt, milk and vanilla for 45 seconds. Add the dry mixture and fold with a rubber spatula in J-shaped motions for 45 to 60 seconds. Next fold in the coated pear cubes with six to eight broad turns. The batter should look thick and pale tan with a few dry streaks disappearing on the final turn. It should fall slowly from the spatula and smell buttery and spiced. Mix past 90 seconds and the muffins can turn tight or develop tunnels. Fold briefly because limited gluten keeps the crumb tender.

Keep the oven at 375°F while you divide the batter. Fill 12 white paper liners evenly in 5 to 6 minutes and stop at about three-quarters full. Use one steady scoop per cup and add smaller spoonfuls only where needed. Press one thin Bartlett pear wedge lightly into each portion. Then scatter 2 tablespoons demerara sugar across all 12 tops. The portions should sit unevenly with small pear cubes peeking through the surface. Each wedge should remain visible rather than sinking under the batter. The sugar crystals will sparkle against the pale tan mixture. Overfill the cups and the domes spread into each other before the centers set. Leave headroom because steam needs space to lift each dome.

Bake the 12 muffins at 375°F for 20 to 24 minutes. Rotate the tin 180 degrees at minute 14 so the back row doesn’t darken first. Start checking at minute 20. A center muffin should reach 200 to 205°F and spring back after a light press. (My first batch baked at 400°F, the tops darkened before the centers set.) The domes should rise above the liners and turn uneven golden brown at the ridges. You’ll smell toasted cinnamon and the pear wedges will look glossy at their edges. A tester should show moist crumbs but no wet batter. Go past 205°F and the crumb dries while the fruit edges harden. Bake steadily because moderate heat sets the center before the sugars scorch.

Cool the muffins in the tin for exactly 5 minutes at room temperature around 70°F. Then lift them out and rest them for 15 minutes before serving. Peel one liner halfway down and split the muffin with your fingers rather than sawing it. The gentle pull exposes pear pockets without crushing the soft crumb. The inside should look moist and pale gold with irregular pieces of translucent Bartlett pear. A little steam may remain, but the crumb shouldn’t smear when touched. Split it before the 15-minute rest and the center can look gummy even when fully baked. Cool briefly because starches need time to set around the juicy fruit.