Prep your pan: Line a 9x13-inch baking pan with parchment, leaving overhang for easy lifting. Lightly dust with powdered sugar if your kitchen is warm.

Make the chocolate layer: In a medium saucepan over low heat, stir chocolate chips and sweetened condensed milk until smooth. Remove from heat and stir in vanilla and salt.

Spread and cool: Pour the chocolate mixture into the lined pan. Spread into an even layer. Let it cool at room temperature for 15–20 minutes until just set but still pliable.

Make the peanut butter layer: In a clean saucepan, melt butter and peanut butter over low heat, stirring until smooth. Remove from heat. Stir in vanilla and salt, then gradually mix in powdered sugar until thick and spreadable.

Layer it: Dollop the peanut butter mixture over the chocolate. Use an offset spatula to gently spread it edge to edge without tearing the chocolate.

Chill briefly: Refrigerate the layered slab for 10–15 minutes. You want it firm enough to roll but not hard.

Roll into a log: Lift the slab out using the parchment. With the long side facing you, use the parchment to help roll it into a tight log, peeling the paper away as you go. If cracks form, warm your hands and gently smooth.

Seal and chill: Wrap the log tightly in parchment or plastic wrap. Chill for 2–3 hours, or until fully firm.

Slice: Using a sharp knife warmed under hot water and wiped dry, slice into 1/2-inch pinwheels. Warming the knife makes clean spirals.

Serve: Arrange on a platter and let sit 5 minutes at room temperature for the best texture.