Hokkaido Baked Cheese Tarts

Name: Hokkaido Baked Cheese Tarts
Prep time: 20 min
Cook time: 50 min
Total time: 1 h 10 min
Cuisine: Asian
Ingredients: 30 pcs frozen 3-inch tart shells (thawed according to package instructions); 1 8-oz block cream cheese (cut into portions); 4 oz brie (with the rind scraped off); 4 oz mascarpone cheese; 4 oz grated parmesan; ¼ cup unsalted butter; 1 cup milk; ½ cup confectioner's sugar (may need more); ⅓ cup cornstarch (may need more); 2 pieces large eggs; 2 tablespoons lemon juice; ½ teaspoon vanilla extract; 1 piece egg yolk from a large egg; 1 teaspoon milk