In a large bowl, whisk together flour, sugar, and salt.
Add eggs and whisk until smooth. Pour in milk, cream, and vanilla. Mix until fully combined.
Cover and chill the batter for 1 hour.
Preheat oven to 325°F. Line a 7.5-inch round pan with parchment paper.
Stir the batter and pour into the pan. Top with sliced apples.
Bake for 45–50 minutes or until custard is set.
Let cool in pan for 15–20 minutes, then remove and cool completely. Chill before slicing for best results.