Heat the milk in a small saucepan over medium heat.

In a small bowl, whisk together the sugar, cornstarch, and salt, then add the beaten egg yolks and stir to combine.

Once the milk has come to a simmer, remove from heat and pour 1/3 of the hot milk into the egg/sugar mix, whisking rapidly.

Pour the tempered egg/sugar/milk mixture back into the saucepan with the rest of the milk; whisk to combine.

Return the saucepan to the stovetop over medium heat and cook, stirring constantly, until the mixture begins to boil and thickens to a puddling-like consistency. Remove from heat and stir in the vanilla extract.

Pour the pastry cream into a bowl and cover it with parchment/wax paper to prevent a skin from forming. Place in the refrigerator until needed.

Remove the puff pastry from the freezer and set it aside to thaw.

Preheat the oven to 375 degrees. Line a baking sheet with parchment paper.

Place the thawed puff pastry on a floured surface and roll out to 1/8-inch thick and in a 9-inch by 9-inch square. Trim any edges as needed.

Cut the dough in half lengthwise and into thirds crosswise, resulting in six 4.5-inch x 3-inch rectangles.

Along each rectangle, cut strips about 1 inch long and 1/2 inch wide, making sure to cut all the way through the puff pastry.

Mix the sliced strawberries with 1-2 tablespoons of sugar, depending on their tartness; toss to coat.

Spread about 1 tablespoon of pastry cream down the center of each rectangle.

Spoon a layer of strawberries on top of the pastry cream.

Face the puff pastry rectangles so the cut edges are on the left and right. Begin at the bottom, cross one strip over the pastry cream and berries, then cross the opposite side strip over the first strip. Continue this pattern, alternating left and right.

Brush each pastry braid with egg wash.

Bake for 25-30 minutes, turning the baking sheet halfway through baking, until golden brown.

Remove from the oven and allow to cool. Top with powdered sugar and serve.