2 cups firmly packed light brown sugar
1 cup unflavored yogurt
Dash of salt
2 tablespoons butter
1 cup firmly packed marshmallows, miniature or standard
1 teaspoon vanilla extract
Lightly oil inside of 1 1/2 - to 2-quart saucepan.
Combine sugar, yogurt, and salt in pan. Cook over low heat, stirring constantly, until sugar is completely dissolved and mixture comes to boil.
Wipe down sugar crystals above liquid line, using clean pastry brush dipped in cold water. Cook until mixture reaches soft-ball stage (238 degrees F). If syrup looks curdled, no not worry; it will become creamy as it is beaten. Remove from heat immediately. Add butter and marshmallows; DO NOT STIR. Allow mixture to cool to 110 degrees F or until pan feels warm to touch. Add vanilla; beat vigorously until fudge is thick and has lost glossy look. Pour into 8-inch square pan to cool. Cut into squares when cool. Yield 1 pound.
Yogurt Nut Fudge: Add 1/2 cup chopped or broken nut meats to mixture before spreading in pan to cool.