Tear bread into about 1-1/2 cups/375 mL coarse crumbs (or pulse in food processor). In large skillet, heat 1 tbsp/15 mL of the oil over medium heat; fry bread crumbs, stirring, until well toasted, about 5 minutes. Set aside.

Add remaining oil to skillet; fry onion until soft, about 4 minutes. Add anchovies, garlic, hot pepper flakes and black pepper; fry until anchovies break apart, 1 to 2 minutes. Add cauliflower and salt; fry, stirring, until cauliflower begins to colour, about 8 minutes. Toss in currants; fry for 1 minute. Push mixture away from centre of pan. Add tomato paste; fry until slightly darkened. Stir in 3/4 cup/175 mL water; cover and cook until water has been absorbed, about 5 minutes.

Meanwhile, in large pot of boiling salted water, cook pasta according to package instructions until al dente; reserving 1/2 cup/125 mL of the cooking liquid, drain. Transfer to serving bowl or individual pasta bowls.

Add tomatoes to cauliflower mixture; simmer, covered and stirring occasionally, for 5 minutes. Stir in enough of the reserved cooking liquid to make a very moist but not runny sauce. Remove from heat; stir in Romano cheese (if using) and parsley. Spoon sauce over pasta; top with bread crumbs.

Makes 4 to 6 servings.