How to Make It
Light a grill. When the coals are hot, set a deep, 10-inch cast-iron skillet on the grill. Add the bread crumbs to the skillet and cook, stirring, until golden brown and crisp, about 4 minutes. Spread the bread crumbs out on a plate and let cool.
Add the pure olive oil to the skillet and heat until shimmering. Add the potato slices in a single layer and cook until just tender, turning once, about 6 minutes. Add the garlic to the skillet and cook, stirring, for 1 minute. Add the broccoli rabe in batches, stirring each batch until wilted before adding more. Stir in the extra-virgin olive oil and heat until sizzling.
Season the eggs with salt and pepper. Pour them into the skillet and cook, stirring gently, until beginning to set, about 1 minutes.
Cover the grill and cook the frittata for 6 minutes. Scatter the bread crumbs on top of the frittata, cover the grill and cook for about 5 minutes longer, until the eggs are firm. Let cool for 5 minutes, then invert the frittata onto a plate. Cut into wedges and serve.