Place the softened cream cheese, sour cream or mayonnaise, and ranch seasoning mix in a bowl. Mix until completely smooth, with no large streaks of cream cheese remaining.

Stir the shredded cheddar, finely chopped bell pepper, green onions, and black pepper into the cream cheese mixture. Divide the finished spread into four roughly equal portions.

Lay one tortilla flat and spread approximately one-quarter of the mixture evenly over it, leaving about a 1/2-inch border around the edge. Layer deli meat over the spread and add baby spinach if using.

Roll the tortilla tightly from one edge into a cylinder, pressing firmly as you go so the filling stays in place. Repeat with the remaining tortillas and filling.

Wrap each tortilla roll individually in plastic wrap and refrigerate for 1 to 2 hours. The chilling time firms the filling and makes the rolls easier to slice cleanly.

Unwrap the chilled rolls and trim the ends if needed. Cut each roll into 8 slices approximately 1/2 to 3/4 inch thick, then arrange the pinwheels cut-side up on a serving platter.