Heat butter in large nonstick skillet over medium heat, placing buns cut side down in pan until golden brown and toasted evenly, 1 min. Remove from pan and keep warm. Add roast beef and barbecue sauce to skillet and toss just to warm through. Spread 2 T Rocket Sauce on bottom bun (invert buns if desired to have toasted side turned out). Divide hot roast beef among sandwiches and top with hot Creamy MoC Cheddar Sauce. Add top bun and serve immediately with freshly baked sweet potato fries, as desired.
Combine all well. Store chilled in airtight container until ready to use.
Creamy MoC Cheddar Sauce
Heat milk in small sauce pan just until bubbling gently. Add cheeses
and paprika, stirring gently until smooth, 1 minute. Use immediately
(can be made ahead and warmed gently when ready to use).