Place the soft butter and powdered sugar in a medium-size bowl and stir until smooth and creamy. Add the vanilla and stir to combine. Sprinkle in the corn starch and stir until nice and smooth.
Add the flour and salt and stir, turning the bowl with and stirring from the bottom up. At first the dough will be very shaggy and dry, but after a minute or so it will come together nicely. Just keep stirring until all of the flour is incorporated and the dough comes together in a big clump.
Divide the dough into 24 equal portions. You can eyeball this or use a digital scale. I weigh the dough then divide by 24. It usually comes out to 25-26g each. Give each portion of dough a little squeeze and hold it in your hand for about 10 seconds (to compress and warm the dough a bit) then roll it between your palms into round balls.
Place the pan(s) in the preheated oven and bake for 18-24 minutes or until the outer edges of each tart are a medium golden brown. (Don't worry the pretty "well" that you made before baking will have puffed up a bit.)
Remove the pan(s) from the oven and immediately reinforce the center wells by gently pushing in again with the ½ teaspoon measuring spoon. You can make the wells as shallow or deep as you’d like at this point.
See Café Tips above in the post for more detailed instructions and tips to ensure success.
If you prefer to use Metric measurements there is a button in each of our recipes, right above the word “Instructions”. Just click that button to toggle to grams, milliliters, etc. If you ever come across one of our recipes that doesn’t have the Metric conversion (some of the older recipes may not), feel free to leave a comment and I will add it.