Pour cherry juice into measuring cup. If necessary, add enough water to reach ⅔ cup of total liquid. (Note: It’s ok if the liquid is all water, but if you have cherry juice…use it for flavor!) Transfer liquid into a saucepan and place over medium-high heat.

Meanwhile, whisk together water and cornstarch. Once cherry juice begins to boil, stir in water/cornstarch mixture. Boil for 1 minute, stirring constantly.

Remove pan from heat and stir in sugar and lemon juice. Add cherries and stir until well combined. Place filling in refrigerator to chill.

In a medium bowl, whisk together the egg yolks, sugar and cornstarch until smooth and pale in color; set aside.

Using a medium saucepan, heat the milk (stirring occasionally) over medium heat until it just begins to simmer.

Slowly pour half of the hot milk into the egg yolk mixture, whisking vigorously the entire time. Pour this egg mixture back into the saucepan with the remaining milk. (Tip: Use a fine mesh strainer when you pour the egg mixture back into the saucepan. This will ensure a smooth pastry cream later.)

Bring mixture to a boil over medium heat and then continue cooking for 1 more minute, stirring constantly the entire time. Remove mixture from the heat, and add vanilla extract and butter; stir until fully combined and smooth. Set pastry cream aside to cool. (Note: The pastry cream will thicken quickly at this stage. It becomes somewhat difficult to stir, but keep stirring to prevent the cream from burning!)

Working with one sheet of puff pastry at a time, roll into a 10”x10” square. Cut square into (4) 5”x5” squares. Repeat with remaining sheet of puff pastry. (Note: In total, this will create 8 smaller squares of dough.)

Working with one square at a time, fold the square into a triangle. With the folded edge of the triangle closest to you, make a cut ¼” in from both the left and right edges of the triangle. The cuts should run from the folded edge and stop ¼” from the top of the triangle.

Unfold pastry. There will be strips of dough on each side of square. Brush the tops of each of these strips with water. Carefully fold the left strip over so that it lays along the right edge of the square (see image in post). Repeat, folding the right strip over to the left edge. This will create a rimmed pastry square with a “knot” at both top and bottom. Place tarts on parchment-lined sheet pan. Repeat with remaining pieces of dough.

Using a fork, dock the center portion of the tarts every 2”.

In a small bowl, whisk together egg with 1 Tbsp water. Brush just the rimmed edges of the tarts with this egg wash. Sprinkle tops of edges with cinnamon and sparkling sugar.

Preheat oven to 350°F.

Spread the Pastry Cream evenly among the tarts. (Tip: If the pastry cream has cooled, you can use your fingers to spread it into the bottom of each tart.) Bake at 350°F for 13-14 minutes, or until edges of tarts have puffed up and are stable.

Remove tarts from oven and add generous scoop of chilled cherry filling. Continue baking at 350° for 28-30 minutes, or until edges of tarts are crisp.

Let cool slightly and top with a scoop of vanilla ice cream (optional) before serving.