Melt butter in a small saucepan over medium heat.
Whisk in flour until combined; cook, stirring, for 1 minute.
Whisk in sugar, then gradually whisk in milk and cream until smooth
Whisk over medium heat until mixture boils and thickens.
Remove from heat; stir in brandy. Serve immediately.
Sauce can be made a day ahead; microwave to reheat, whisking until smooth. The sauce will thicken after refrigeration so it may need a little extra cream or milk to thin it down slightly.Test Kitchen tip