In a small saucepan, using a silicone spatula, stir together the butter, brown sugar, corn syrup, and cream until the sugar dissolves. Bring the mixture to a boil over medium-low heat, stirring constantly. Simmer for about 4 minutes, stirring gently, until thickly bubbling. (An instant-read thermometer should read 244°F/118°C.) Remove the pan from the heat and pour the butterscotch into the raspberry puree, stirring to combine.

Allow the raspberry butterscotch to cool to room temperature, about 45 minutes. If desired, add more of the reserved raspberry puree to taste. Pour the raspberry butterscotch into a disposable pastry bag or quart-size reclosable freezer bag and cut a very small semicircle from one corner. Lace the raspberry butterscotch onto the scones.