In a large bowl, mix together the flour, sugar, cardamom, and salt until combined. Cut the butter into small pieces above the bowl, stopping to stir and coat the butter bits in the flour mixture every few minutes.

Pinch the mixture together with your fingertips until it resembles the texture of damp sand. Add the water, a tablespoon at a time, mixing it with a fork, until the dough just holds together when you squeeze a fistful of it in your hand.

Roll out the dough until it is 1/8-inch thick and transfer it to a 10-inch pie dish. Press the crust into the pan, trim off the excess leaving a 1-inch overhang, and reserve the excess dough. Fold the 1-inch overhang under the edge of the crust all the way around and pinch the edges.

Roll out the remaining dough until it is 1/8-inch thick and cut out any decorative shapes you want to place along the edge of the crust. 

In a small bowl whisk together the egg with 1 tablespoon of water. Lightly brush the edges of the pie crust and place the decorative pieces along the edge, pressing down gently to adhere them with the egg wash. Lightly brush the decorative pieces with the wash.

Prick the inside of the crust all over with a fork. Gently cover the pie crust with beeswrap, foil, or plastic wrap and place it in the freezer for at least 2 hours or overnight.

Preheat the oven to 350 degrees Fahrenheit. Mix together the sugar, cornstarch, flour, and salt in a medium-sized saucepan. Then whisk in the water and the milk and place the saucepan over medium high heat, whisking often, until it comes to a boil. Lower the heat to a simmer and take one cup of the mixture out of the pan.

Gradually whisk the cup of the mixture into the beaten egg yolks until they are thoroughly combined. Add the lavender blossoms and pour the lavender and yolk mixture back into the saucepan and continue to simmer the filling until thickened, whisking constantly, about four more minutes.

Remove the filling from the heat and stir in the lemon juice, lemon zest, butter, and the vanilla extract until completely combined. Set aside.

Remove the crust from the freezer and line the inside with a piece of foil, and place pie weights or dried beans inside the pie in an even layer on the bottom. Place the crust in the oven and par-bake the crust for 15 minutes. Remove from the oven, remove the pie weights and foil, and place the pie back in the oven for another 10 minutes. Then remove the crust from the oven and set it aside. Preheat the oven to 400 degrees Fahrenheit.

To make the meringue, heat the sugar and water in a small saucepan over medium low heat until dissolved. Raise the heat to high and wait until the syrup reaches 235 to 240 degrees Fahrenheit, making sure to NOT stir the mixture.

While the syrup is boiling, beat the egg whites in the bowl of a stand mixer fitted with the whisk attachment at medium high speed until there's little bubbles at the top of the egg white mixture. Add the cream of tartar, then continue beating at medium high speed until soft peaks form. Stop the mixer until the syrup has reached the right temperature.

When the syrup is ready, turn the mixer on medium high speed and begin adding the syrup to the egg whit mixture in a thin steady stream. Continue beating until the meringue is glossy and holds a stiff peak.

Add the lavender lemon filling to the pie crust and spread to evenly distribute on the bottom of the pan. Switch out spatulas, and add the meringue on top in an even layer. Use the back of a spoon to create pretty swirls on top of the meringue.

Place the pie back in the oven and bake until the meringue turns gold at the tips, keeping a close eye on it. Remove the pan from the oven and let the pie cool at room temperature for 1 hour before placing in the refrigerator to chill for at least 4 hours before slicing and serving.