Custardy crème fraîche apple pie

INGREDIENTS

for the filling:

1/2 cup

(about 63 grams) all-purpose flour

2/3 cup

(about 133 grams) granulated sugar (or ½ cup; see Notes)

1/8 tsp

salt

3 cups

(about 1 lb) apples, cored and sliced (and peeled, if you wish)

large egg

2 tsp

vanilla extract

1/2 cup

or 113 grams) Vermont Creamery Madagascar Vanilla crème fraîche, plus more for serving

1/2 cup

or 113 grams) sour cream

for the topping:

1/2 cup

(about 63 grams) flour

1/4 cup

granulated sugar

2 tbsp

brown sugar

1 tsp

ground cinnamon

6 tbsp

(¾ stick, or 85 grams) cold butter (see Notes)