Step 1

Preparation Combine anchovies, garlic, oil, and red pepper flakes in a large skillet. Cook over medium heat, stirring often, until anchovies have disintegrated into oil and garlic is lightly browned, 6–8 minutes.

Step 2

Meanwhile, cook pasta in a large pot of boiling salted water, stirring occasionally, until al dente. Drain, reserving 1 cup pasta cooking liquid.

Step 3

Remove skillet with anchovy mixture from heat and stir in butter and lemon juice until butter is melted. Add pasta and 1/2 cup pasta cooking liquid and stir constantly until a thick glossy sauce forms, adding more pasta cooking liquid as needed.

Step 4

Place radicchio in a large bowl. Add pasta and sauce and toss to coat, adding more pasta cooking liquid as needed. Add arugula and basil but don’t toss; season with salt and black pepper.

Step 5

Divide pasta among plates or bowls, very gently tossing so arugula gets coated in sauce but doesn’t wilt too much.