Zest tangelo. Rub zest into sugar.Using a fork, juice tangelo w/ pulp. Add juice to cream, set aside. Drain currant/raisin mix.
Whisk dry ingredients together in food processor with pastry blade. Pulse the butter into the flour until the mixture is crumb-like.
Shape into rectangle 1" high. Using a bench scraper, cut into square pieces, arrange on baking sheet. Brush with melted butter, sprinkle with cane sugar. Bake for 10 minutes, rotate, and bake for 7-8 more minutes until golden brown on top.