These mini pies are the perfect picnic dessert.
Combine flour with salt in the bowl of a food processor; pulse to combine. Add butter and pulse until the mixture resembles coarse crumbs. Add water, pusing until the pastry just comes together in a ball.
Turn out onto a lightly floured surface. Roll out 1/8 inch thick. Cut into twelve 4-inch rounds. Transfer each round into a muffin tin, pressing pastry up the sides on each cavity. Place tin in the freezer until ready to use.
Heat oven to 425°F.
Whisk together sugar and flour in a large bowl. Add raspberries and toss to combine. Add lemon juice and egg; stir to coat. Set aside.
Whisk together oats, sugar, flour and salt in a large bowl. Add butter and using hands, break up butter and work into the oat mixture until the mixture is hydrated and clustered.
Remove muffin tin from the freezer and fill evenly with raspberry filling. Top evenly with the crisp topping.
Bake in the oven until the filling is thick and bubbling and the crisp topping and pastry edges are golden brown, about 35-40 minutes. Remove from the oven and run a paring knife around the edge of each pie to prevent them from sticking. Let cool in the pans for 10 minutes before removing to the cooling rack to cool to room temperature.
Bring milk, cream and vanilla seeds to a simmer in a medium saucepan over medium heat.
Whisk together eggs and sugar in a medium, heat proof-bowl. Slowly pour in milk mixture, whisking constantly. Transfer back into the saucepan and return to low heat. Cook, stirring frequently until the mixture has thickened slightly and coats the back of a wooden spoon, about 5 minutes.
Strain through a fine mesh sieve, cover and chill until ready to use.