Custard-y Fruit Tarts

I made this on a leap of faith. The instructions seemed too easy. The process seemed too quick. But it worked. A quick delicious creamy custardy pie filling that accompanied blueberries and pre-made grocery store graham cracker crust perfectly. I loved that it wasn't terribly sweet.
Huge props to http://www.salad-in-a-jar.com/family-recipes/fruit-and-cream-mini-tarts, where this recipe is from. I, obviously, didn't make the crust, but it also seems worth a try sometime. I halved the recipe for 5 mini graham cracker crust tarts.
Anyway, the steps, from the above link, with my own notes and halved quantities.

Ingredients: 
1 & 3/8 cups milk I used part evaporated milk and part half&half
1/3 cup sugar
1/8 cup cornstarch
1/16 teaspoon salt
2 egg yolks
1 tablespoon butter
1/2 teaspoon vanilla extract

Instructions:
1. Add milk, sugar, cornstarch, salt and egg yolks --in that order-- into a blender or the hand blender cup.
2. Blend for 5 seconds.
3. Pour into a microwave-safe bowl.
4. Microwave for 6 minutes, whisking until smooth after 3 minutes, then every minute thereafter.
5. Add butter and vanilla. Whisk until smooth. Note to self, don't worry about using a tablespoon of butter straight from the fridge. The mixture will be hot enough that it will melt quickly as you whisk.

6. Let cool a little, but not too much. Then, pour into the crusts. Immediately top with fruit. 

Honestly, I think I let it cool too long before pouring into the crust. At that point, it was more like scooping, rather than pouring, Thus the slight lumpiness. It still tasted great. The blueberries are some we picked locally and froze last summer. Still delicious!