Matt Lewis, co-owner of Baked, joins Martha to make a Sweet and Salty Cake.
Combine 1/4 cup water, sugar, and corn syrup in a medium saucepan; stir to combine. Bring to a boil over high heat. Cook until the mixture reaches 350 degrees on a candy thermometer, about 10 minutes.
Meanwhile, in another small saucepan, mix together cream and salt. Bring cream to a boil and cook until salt has dissolved, 3 to 5 minutes. Remove from heat and set aside.
When the caramel mixture has reached 350 degrees, remove from heat and allow to cool for 1 minute. Carefully add the hot cream to the caramel; stir to combine. Whisk in sour cream. Cool, and store in an airtight container, refrigerated, for up to 3 days.