Combine sugars, milk, and cream in a 2-quart sauce pan and bring to medium heat until sugars dissolved. Bring to a rolling boil stirring constantly until candy thermometer reaches 236°F (soft-ball drop stage) or for about 8 minutes. Remove from heat and add butter stirring until melted. Let set unstirred until the temperature is 110°F (uncomfortable to touch but won't burn you) then add vanilla and stir vigorously (5-10 minutes) until mixture cools enough to lose it's glossy texture. Fold in nuts and pour.

Remarks:

A simple fudge with a unique taste from the molasses in the brown sugar. Penuche is a standard around Easter. Also a regional favorite - popular in Southern States and in Mexico.

If you don't have brown sugar you may substitute 1 cup of white sugar + 1/4 cup molasses.

Warning: Don't substitute 2 1/2 cups of light brown sugar for the mixture of brown and granulated sugar. This would result in too much molasses which interfers with the sugar slurry reaching it's soft ball stage... therefore what would appear to set by the standard techniques (boiling temperature, drop-test, etc.) won't set... fluid fudge... fudge failure!