4 tablespoons unsalted butter, melted
6 tablespoons sugar, divided use
3⁄4 cup whole milk
3 large egg yolks, room temperature
3 tablespoons flour
1⁄2 cup Grand Marnier®
1 teaspoon orange zest
4 large egg whites, room temperature
1⁄4 teaspoon cream of tartar
Preheat oven to 450°F. Coat 6 1-cup soufflé dishes with melted butter and sprinkle 1 teaspoon sugar in each. Reserve.
In a small saucepan, heat milk to a simmer on medium-low heat then remove from heat. Reserve.
Using an electric mixer on medium speed, beat egg yolks with 3 tablespoons sugar until mixture is thick and lemon colored – approximately 3 minutes. Whisk in flour by hand, until well blended.
Gradually add 1⁄4 of the hot milk into the egg mixture, whisking constantly, then add egg mixture back into the hot milk, whisking constantly until fully blended. Cook mixture over medium-low heat, stirring constantly with a wooden spoon until mixture coats the back of the spoon – approximately 2 minutes. Remove from heat and pour into a large bowl. Add Grand Marnier® and orange zest. Whisk together well and cover with plastic wrap. Let cool about 45 minutes.
Using an electric mixer on high speed, whip egg whites and cream of tartar until soft peaks form – approximately 1 minute. Add remaining 1 tablespoon sugar, whipping until stiff but not dry – approximately 2 minutes.
Gently fold egg white mixture into egg yolk mixture and spoon evenly into prepared soufflé dishes.
Bake until golden – approximately 10-15 minutes and serve immediately.