Make the browned butter: Melt 1 stick butter in a medium saucepan over medium-high heat and cook until it begins to bubble. Reduce the heat to medium and cook, swirling the pan, until the butter turns golden and smells nutty, about 3 minutes. Remove from the heat and let cool.
Whisk both flours, 1/2 cup brown sugar and the salt in a medium bowl. Beat the egg whites in a large bowl with a mixer on high speed until stiff peaks form; stir in the vanilla. Fold in the browned butter and the dry ingredients, then cover the batter with plastic wrap and refrigerate 1 hour.
Preheat the oven to 350˚ F. Butter a 12-cup muffin pan. Melt the remaining 2 tablespoons butter and combine in a large bowl with the pears and remaining 2 tablespoons brown sugar; toss. Divide the batter among the muffin cups; top each with 3 pear slices. Bake until puffed and golden, 12 to 14 minutes. Let cool 5 minutes in the pan, then remove to a rack to cool completely. Dust with confectioners' sugar.