Preheat the oven to 450°F. Cover the raisins with boiling water and let stand for 10 minutes to soften. Sift together the dry ingredients and use a food processor to cut in the cold butter until it resembles peas. Pour into a mixing bowl.
Mix in the buttermilk and raisins. Stir until fully combined. The dough will be sticky.
Lightly flour a non stick surface with additional Bisquick and turn the dough out onto the surface..
Knead the dough coating with Bisquick until it's not sticky. Around 10 turns.
Pat the dough into a round even height and width, then divide the dough in half then into 4 equal pieces. [Tip: Use just enough dry biscuit mix and avoid incorporating too much or the biscuits will be dry]
Mix together the cinnamon swirl ingredients.
Butter a metal non-stick 9 x 9 baking pan.
Gently, press 1/4 of the dough into the pan, then spread with 1/4 of the cinnamon swirl mixture. Repeat with each dough layer, pressing the edges of the dough together. Use floured hands, if needed. End with the cinnamon mixture.
Use a sharp knife and score the biscuits into 16 portions. Place into the preheated oven then immediately lower the temperature to 375°F.
Bake for 35-40 minutes or until cooked through and golden. Check at 25 minutes and place aluminum foil on top if needed to prevent over browning.
Mix together the glaze ingredients and drizzle on top.
The biscuits can be served as a pull-apart biscuit, drizzling the glaze over the top, or separated and glazed, according to your preference.