How to Make It
Light a grill. When the coals are hot, push them to one side of the grill. Put the bread crumbs in a large cast-iron skillet. Set the skillet on the grill opposite the coals; cover and cook, stirring occasionally, until the bread crumbs are nicely toasted, about 5 minutes. Transfer the bread crumbs to a large bowl and stir in the light brown sugar and half of the melted butter.
In a large bowl, toss the apple slices with the lemon juice and zest. Add the dark brown sugar, cinnamon, nutmeg and cloves and toss well.
Set the skillet back on the grill opposite the coals and scatter half of the bread crumb mixture over the bottom. Spread the apple slices in the skillet in an even layer. Top with the remaining bread crumbs and drizzle with the remaining melted butter. Cover the grill and cook until the apples are tender and bubbling and the crisp is browned, about 45 minutes. Remove the skillet from the grill and let rest for at least 10 minutes.
Meanwhile, in a medium bowl, mix the yogurt with the confectioners' sugar. Serve the apple crisp, warm or at room temperature, with the sweetened yogurt.