In a large mixing bowl, combine the water, sugar, and yeast. Add the butter, eggs, and half of the flour. Mix well using the paddle attachment until smooth and combined.
1 1/2 cups warm water , 1/2 cup granulated sugar, 1/2 cup salted butter, 2 1/4 teaspoons instant yeast, 5 to 5 1/2 cups (705g to 778g) all-purpose flour, 1 teaspoon salt, 2 large eggs
Switch to the dough hook attachment. Add the remaining flour and mix well until combined. Knead for 5 minutes on medium speed with the dough hook attachment or 8-10 minutes by hand until the dough is satiny and smooth. Cover the bowl with plastic wrap and let the dough rise in a warm place for 1 1/2 to 2 hours until doubled in size.
Meanwhile, make the custard by combining the milk, cream, and half of the sugar in a medium saucepan over medium heat. Heat while stirring until steaming but do not let this come to a boil.
1 1/2 cups whole milk, 0.5 cup granulated sugar, 1 cup heavy cream
In another bowl, whisk the remaining sugar, eggs, flour, and salt until light. Gradually whisk about 1 cup of the hot liquid into the egg mixture to temper the eggs so they don't scramble while adding them to the hot mixture.
0.5 cup granulated sugar, 2 Tablespoons all-purpose flour, 4 large eggs, 1/4 teaspoon salt
Return the tempered egg mixture to the saucepan and continue to cook over medium heat, stirring constantly, until thickened or an instant digital thermometer reads 180℉ when testing the custard. Remove from the heat and stir in the vanilla. Cool to room temperature.
1 Tablespoon pure vanilla extract
Preheat the oven to 350℉ (177℃). Spray four 9-inch cake pans or springform pans with baking spray.
Make the crumb topping by combining the flour and sugar in a mixing bowl. Use a pastry cutter to cut the cold butter into the dry ingredients until they resemble coarse crumbs. Set aside.
1 cup all-purpose flour, 1/2 cup granulated sugar, 1/4 cup salted butter
Turn out the dough onto a lightly floured surface and divide into 4 balls. Working with one ball at a time, roll out the dough into about a 10-inch circle. Carefully transfer the dough to one of the prepared pans, pressing the edges about 1/2" to 3/4" up the side of the pan. Arrange about 1 cup (8 ounces) of the fruit on the dough. Spread 1/4 of the custard (about 3/4 cup) evenly over the fruit. Sprinkle with 1/4 of the crumb topping and sprinkle with a little cinnamon, if desired.
Fruit to fill the bottom
Bake for 25-30 minutes until golden brown just around the edges and the centers are mostly set with only a slight jiggle. Remove from the oven and let cool completely. Serve room temperature, chilled, or warm with a scoop of ice cream.