Preheat your oven to 350°F. Add all of the ingredients for the crust to a large bowl. Knead with your hands, or, use a food processor to work the dough. It’s okay if there are still small chunks of cold butter in the dough. Press into a greased tart pan or dish. Bake for 15-20 minutes, until the crust is golden brown. Set aside to cool for at least 15 minutes.
Warm your heavy cream gently in a sauce pan with your raspberries. Cook slowly and keep the heat low to avoid boiling (and curdling).Use a wooden spoon or masher to mash your raspberries as they soften. This should take roughly 7-10 minutes. Strain raspberries and cream mixture through a metal sieve into a mixing bowl.
In a separate bowl, heat white chocolate chips gently with butter either in the microwave or in a double boiler. We like to heat in 15-20 second intervals in the microwave at full power, stirring often. After white chocolate is melted, stir continuously until smooth. Combine the raspberry cream mixture and the white chocolate and butter mixture, whisk until smooth.
Stir in optional lemon juice, vanilla extract, and salt, whisk until smooth. Add the filling to the crust, then refrigerate until set, about 2 hours. Garnish with white chocolate drizzle, raspberries, and edible flowers if desired. Enjoy your Raspberry White Chocolate Tart!