Make butter block. Mix 1 cup softened butter with ½ teaspoon salt and 2 tablespoons flour. Shape into a 13x18 inch rectangle between parchment paper. Chill until firm but flexible.
Enclose and seal. Roll the dough into a large 18x26 inch rectangle. Place the butter block on the lower half, fold the dough over to enclose it, and pinch seams to seal.
Fold and roll. Roll out gently and perform a letter fold (fold into thirds). Chill for 30 minutes. Repeat this fold 2 more times (chilling 30 mins between each). Chill for 1 hour after the final fold.
Make the filling. Mix the filling sugar, cinnamon, salt, and zest of 1 orange. Roll the dough into a large rectangle. Spread with 6 tablespoons softened butter and sprinkle with the sugar mixture.
Shape. Cut into 12 strips (for standard tin) or 6 strips (for jumbo). Roll into spirals. Place in a buttered muffin tin. Proof for 2-4 hours until puffy.
Bake Preheat oven to 375°F (190°C). Bake 18-20 minutes (standard) or 22-24 minutes (jumbo) until golden. Zest the remaining orange while they bake.
Toss in coating. Cool in pan for 5 minutes only. While warm, brush with melted butter and toss in a mixture of the coating sugar, cinnamon, and remaining orange zest.