Preheat oven to 350°F (180°C).
Line 6 (1-cup) copper molds or 8-ounce ramekins with 2 (8- to 10-inch-long) 1-inch-wide strips of foil to make an “X,” letting excess extend over sides of molds (A). Line bottom of each mold with parchment paper (B).
In the work bowl of a food processor, pulse pretzels and pecans until finely chopped and well combined. In a medium bowl, stir together pretzel mixture, sugar, and melted butter until well combined and mixture holds together when lightly pressed. Divide mixture among prepared molds (about 2 tablespoons or 28 grams each). Press firmly into an even layer (C). Place molds on a rimmed baking sheet.
Bake until fragrant and set, about 15 minutes. Transfer molds to a wire rack, and let cool completely.
Prepare Vanilla Semifreddo mixture from step 2 through the first sentence of step 4. Add 1⁄2 cup (160 grams) strawberry spread to Vanilla Semifreddo, and stir once or twice to just barely mix in. Spoon semifreddo mixture into prepared molds, scooping from where strawberry spread has swirled to preserve large streaks of fruit. Alternately spoon remaining strawberry spread and remaining semifreddo mixture into molds. Smooth tops with an offset spatula. Place molds on a baking sheet, and freeze until firm, at least 6 hours, or up to overnight.
Let molds stand at room temperature for 5 minutes or gently warm sides and bottoms of molds with your hands, a warm towel, or a handheld kitchen torch. Using excess foil pieces as handles, gently lift each semifreddo straight up and out of mold. (If semifreddo is sticking, let stand for 5 minutes or warm the side with your hands and try again.) Using an offset spatula, smooth sides, if desired. Serve immediately, or freeze in an airtight container for up to 1 week.