Frosted Jam Cake Icing

This cooked cream icing is the traditional crown for a Southern jam cake, but it works as a luxurious topper for any layer cake or pound cake that needs dressing up. Three ingredients (heavy cream, sugar, and butter) cooked to the soft-ball stage and beaten produce a glossy, caramel-flavored frosting that’s halfway between buttercream and fudge.

The technique is classic candy-making, which means the candy thermometer is your best friend here. Two minutes at a full rolling boil takes the syrup to 234°F (112°C), the soft-ball stage, where the sugar will firm up enough to spread but stay soft enough to slice cleanly through.

Miss this temperature window and you have either a runny glaze (under) or a granular fudge (over).

The cooling-and-beating step is what gives the icing its signature spreadable consistency. Letting the syrup cool slightly before beating prevents the frosting from being too liquid, while beating until it just begins to thicken stops the crystallization at exactly the right point.

Butter goes in last for richness and shine, then the icing must be spread immediately before it sets up too firm.

Pro Tips

• Use a heavy-bottomed saucepan. Thin pans cause hot spots that scorch the cream.
• Calibrate your candy thermometer first by testing in boiling water. It should read 212°F (100°C) at sea level.
• Have the cake assembled and ready before you start the icing. Once it sets, you can’t re-spread.
• Leave the sides unfrosted as the recipe suggests. The naked sides showcase the cake layers and the icing-and-pecan top.

Variations

• Add a teaspoon of vanilla extract or bourbon at the butter stage for added depth.
• Stir in a pinch of sea salt for a salted caramel-style icing.
• Substitute toasted walnuts for pecans for a different nut profile.