Preheat oven to 425F.
Place bacon on wire rack on half of a baking sheet and cauliflower florets tossed with 2 Tbsp olive oil and salt on the other half.
Roast 15 minutes until bacon is golden and cauliflower is caramelized.
Let bacon cool 10 minutes, then dice into pieces.
In large saucepan over medium-low heat, combine remaining 2 Tbsp olive oil, butter, anchovy paste, garlic, and crushed red pepper.
When butter foams, add kale and cook 3-4 minutes until wilted and bright green.
Stir in lemon zest and juice, cover, and turn off heat.
Boil bucatini in salted water 9-10 minutes until al dente, reserving 3/4 cup pasta water before draining.
Add pasta water to lemon-kale mixture and bring to gentle simmer over medium heat.
Add drained pasta, roasted cauliflower, Parmesan, and parsley, tossing until well coated.
Divide among bowls and top with crispy bacon and extra Parmesan.