Blind bake tart shells. For standard frozen shells it is about 11 minutes at 374 degrees. When they are light golden brown they are done. Allow tart shells to cool.
In a food processor, whisk the milk, syrup and yolks til well blended.
Whisk flour and cornstarch in a medium bowl. Gradually whisk one cup of the milk mixture into the dry ingredients.
Add the flour/milk mixture back into the food processor and whisk to blend thoroughly.
Transfer mixture to a large saucepan. Whisk over medium heat until the custard starts to thicken and boils. This may take 8 minutes or more depending on the size of your saucepan etc. Mixture should look like soft pudding when you remove it from the heat.
Spoon custard into the cooled tart shells. Refrigerate until chilled. (You can do this a day ahead but ensure tarts are tightly covered.)
Whip cream and maple syrup until it holds stiff peaks. Spoon onto top of each tart with a swirl. Refrigerate until ready to serve.