Step 1
Pulse flour sugar and salt together in a food processor. Add butter and cream cheese; pulse until mixture looks like wet sand.
Step 2
Sprinkle 1 tablespoon ice water over the mixture. Pulse until dough just starts to clump together; add a bit more water if it looks very dry.
Step 3
Turn dough out onto a sheet of plastic wrap. Gather and gently press together into a cohesive ball. Use the wrap to press dough out into a thick disk. Wrap well and chill until firm at least 1 hour and up to overnight.
Step 4
Line a baking sheet with parchment paper. Lightly dust a flat work surface with flour. Roll dough into a 12-inch circle moving dough around frequently to prevent sticking. Trim edges if they look very rough. Fold up dough into quarters. Brush off excess flour and transfer to the baking sheet. Unfold gently.
Step 5
Refrigerate dough while preparing the filling.
Step 6
Preheat the oven to 400 degrees F (200 degrees C).
Step 7
Combine berries lemon juice and vanilla extract in a large bowl. Mix sugar cornstarch and salt in a small bowl. Pour over berries and toss gently to combine.
Step 8
Remove dough from the refrigerator. Spread jam over the middle leaving a thick border around the edges. Mound berries over the jam. Fold the edges of the dough over the berries and pleat it every few inches.
Step 9
Whisk egg and water together. Brush the border of the galette with the egg wash and sprinkle with turbinado sugar.
Step 9
Bake in the preheated oven until crust is deep golden and juices are bubbling 25 to 30 minutes. Check the underside of the galette is also browned. Transfer baking sheet to a wire rack and let cool before slicing.