If you can't find radishes with greens attached, simply substitute carrots and a few handfuls of spinach or another tender green.
1. In a large pot of boiling salted water, cook 3/4 pound pasta according to package instructions. Reserve 1 cup pasta water; drain pasta and return to pot. Add 2 tablespoons butter and toss until melted; keep warm.
2. Meanwhile, in a large skillet, melt 1 tablespoon butter over medium-high. Add 2 cloves sliced garlic and 1 large bunch sliced radishes, greens reserved, and cook until radishes are crisp-tender, 3 minutes. Add radish greens and cook until wilted. Season with salt and pepper, then add to pasta and stir to combine. In skillet, melt 1 tablespoon butter. Add 1 pound peeled and deveined frozen shrimp, season with salt and pepper, and cook, stirring occasionally, until opaque, 4 minutes. Add shrimp to pasta and toss, slowly adding pasta water until a light sauce forms.