How to Make It
In a microwave-safe bowl, microwave the white chocolate in 20-second bursts until softened. In a small saucepan, bring the cream and corn syrup to a simmer; stir the cream mixture into the white chocolate. Stir in the peanut butter and salt. Transfer the filling to a piping bag fitted with a medium tip.
Spoon the tempered chocolate into a piping bag fitted with a small tip. Line a baking sheet with parchment paper. Set half of the foil cups on the sheet and fill them with chocolate. Tilt the cups to coat them completely, then pour the excess chocolate into a bowl. Turn the coated cups upside down on the baking sheet and let stand for 30 seconds; turn the cups right side up and let stand until the chocolate is firm, about 10 minutes. Repeat to make the remaining chocolate cups.
Half-fill the cups with the peanut butter. Spoon a rounded 1/2 teaspoon of jam over the filling. Pipe chocolate on top of the jam; tap gently to level the chocolate. Top with a few flakes of Maldon salt. Let stand until set, about 15 minutes. Store for up to 1 week.
Tempering chocolate gives it a beautiful sheen and a firm structure: Put chopped chocolate in a stainless steel bowl set over a saucepan of simmering water. Stir occasionally until melted and 115°. Off the heat, stir the chocolate until it has cooled to 88°, about 15 minutes. If the chocolate hardens, melt and temper it again.