To prepare the Pastry Cream: In a small saucepan, bring the half-n-half, 2 tablespoons sugar and the salt to a simmer over medium-high heat, stirring occasionally. In a small bowl, stir together the cornstarch and remaining sugar. Add the 2 egg yolks and stir until mixture is smooth.

Temper the egg yolk mixture by ladling about 1/4 cup simmering half-n-half into the bowl and whisk well to combine. Transfer the mixture into the simmering liquid, whisking vigorously. Allow the pastry cream to bubble for 5 seconds, then remove the pan from heat. Stir in the butter and vanilla. Transfer to small bowl, cover well with plastic wrap and refrigerate until chilled.

To prepare the Puff Pastry: Place the still-folded sheet of puff pastry on the counter facing you vertically (long end up and down). Don't flour the counter at this point; if you're afraid of sticking, use parchment paper. Open the two panels of the dough and lightly brush both sides of the right panel with water and fold it back into position. Cover with the left panel and press the pastry down to seal. Lightly brush the top of the pastry with water then roll the short edge away from you as if making a jelly roll. Make the roll as tight as you can. You should have a thick, 3-inch wide log when you're finished. Roll the log back and forth on the counter to extend it to 3 1/2 - 4 inches. Wrap it in plastic wrap and refrigerate while you wait for the pastry cream to chill.

To prepare the Tart Shells: Preheat your oven to 400°F. If the edges of your log are uneven, use a serrated knife to trim then cut the log into 12, roughly 1/4-inch slices. Don't discard the edges, though. You may need them to make the 12th piece if you slice unevenly. I've done this. It's better to work with pastry slices when they're chilled work with one or two at a time, keeping the rest in the refrigerator.

Lightly flour your work surface and flatten the pastry slice with your fingers into a 3 - 4 inch circle. Alternatively, you can also use a rolling pin for this. I've tried both methods with minimal difference in outcome of the baked tart shells. The latter is a lot faster, I've found. Press the dough agains the bottom and sides of the muffin pan. If you're using a 1/3 cup muffin pan, you should have enough dough to reach the top of the tin, allowing you to create lip around the top. If you're using a regular muffin pan, just press the dough as far up the well as possible.

Prick the dough with the tines of a fork to avoid too much puffing then fill the muffin wells with dried beans, rice or pie weights.

Bake the shells for about 16 minutes or until the edges are puffed and golden. Remove the shells from the pan followed by the pie weights, rice or beans and cool them on a wire rack until they're ready to fill.

To assemble the Tarts: Add a teaspoon or two of the chilled pastry cream to each shell. Don't be tempted to add more than this or you might not have enough to fill all 12 shells. Top with as many blueberries as you like. Arrange on a platter and serve.