1. Preheat oven to 375 degrees F. Mix flour, rosemary, and baking powder together in a small bowl.
2. Beat butter and sugar together in a medium bowl with a wooden spoon. Add the egg yolk and the vanilla and mix well. Add the flour mixture, mix well, then refrigerate while you prepare the fruit.
2. Combine chopped apples and pears with the rosemary, lemon zest, dissolved cornstarch, and brown sugar in a large bowl. Add the browned butter and mix well.
3. Transfer fruit mixture to a deep baking dish, then drop teaspoons full of the the cobbler topping on top (if you use the gluten-free flour mix, the topping may be less stiff than if you use regular flour...that's ok).
4. Bake for 45-55 minutes, or until apples and pears are very tender and bubbling, and the topping, which will spread out across the fruit, is golden brown.