In a 2 quart saucepan, mix sugar and flour with a wire whisk.

Add milk, whisking until smooth.

Cook over medium high heat, stirring often, until mixture boils and thickens.

Reduce heat to low and cook, stirring constantly, for 2 minutes.

Remove from heat and cool completely, about 45 minutes.

While mixture is cooling, melt semisweet and unsweetened chocolates over low heat, stirring frequently.

Cool slightly.

In a large bowl, with mixer at medium speed, beat butter until creamy.

Gradually beat in cooled milk mixture.

When the mixture is smooth, beat in brandy and vanilla until blended.

Spoon half of frosting into a small bowl.

Stir cooled chocolate into frosting remaining in large bowl.

*This makes about 1 1/2 cups of each flavor.*