To Make Crust

1. Whisk flour and sugar together in a small bowl.
2. Dump flour onto work surface and add butter chunks.
3. Toss to coat.
4. Using a rolling pin, flatten butter into flour, making long strips.
5. Use a bench scraper to scrape dough off rolling pin and surface as needed.
6. Gather the dough strips into a loose pile and add 4 -5 tablespoons of water to it.  It will look like a crumbly disaster, but don’t worry.
7. Gently mix the water into the dough.
8. Roll dough out into a long rectangle.
9. Fold each end in towards the center.
10. Turn the dough 90 degrees and repeat this process again.
11. Turn the dough a final time, and repeat the process.  The dough should be adhering together nicely, but you will still have some crumbling.  That is okay.
12. Gathering up the crumbles, wrap the loosely formed rectangle in plastic wrap.
13. Then shape the wrapped dough into a disc about 1 inch thick.
14. Refrigerate at least 2 hours or up to three days.

To Make Vanilla Pastry Cream

1. Pour milk into saucepan.
2. Scrape contents of vanilla pod into milk and then add in the pod.
3. Heat milk to almost boiling.
4. In a separate bowl, mix sugar, whole egg, egg yolks, and cornstarch in a bowl.
5. As soon as milk starts to simmer, remove vanilla bean pod and discard.
6. pour a small amount into the egg mixture to temper the eggs, whisking quickly so that the eggs do not cook.
7. When the eggs have been tempered, add the egg mix into the hot milk in sauce pan and continue to whisk vigorously.
8. Heat the custard over medium heat, and continue to whisk.
9. While whisking, allow the custard to come to a boil.
10. Lower the heat and continue to whisk for another 45 seconds.
11. Remove the mixture from the heat and add butter.
12. Whisk until the butter is completely incorporated.
13. Pour custard into a bowl and cover completely with plastic wrap (make sure the wrap is directly on the custards entire surface to prevent a skin from forming on top.
14. Let custard cool to room temperature.
15. Once cooled completely, place in the refrigerator to completely chill.

To Prepare Fruit Filling

1. Peel and slice the peaches
2. Place the fruit in a bowl.
3. Mix sugar and corn starch together.
4. Sprinkle over the fruit and toss to coat.
5. Cover and refrigerate until ready to use.

Put it All Together

1. Sprinkle flour on a sheet of parchment paper.
2. Take the dough dish out of the refrigerator and roll into a rough circle about 12 inches in diameter.  It does not need to be perfect.
3. Spread the vanilla pastry cream in the center of the circle staying approximately 3 inches from the edge.
4. Place peaches around the perimeter of the pastry cream.
5. Then add the strawberries and blueberries.  Leave the juice in the bowl as this may make the galette too soggy.
6. Take an edge of the circle and pull it up gently over the peaches.  
7. Repeat this process all the way around the circle.  You will need to crimp the dough as you go.
8. Gently pick the parchment paper up and slide it onto a cookie sheet.
9. Preheat your oven to 425 degrees Fahrenheit.
10. Beat an egg and 1 Tablespoon of milk together.
11. Brush this mixture on the crust perimeter.
12. Sprinkle the top of the galette with Turbenado sugar.
13. Place the galette in the refigerator to chill for at least 1 hour so that it does not spread when baking.  You can also chill overnight, but make sure you cover it.
14. Place in the oven and bake for approximately 28-30 minutes.