8 partially baked individual tart crusts (alternately you can use 1- 9″ partially baked tart crust)***
1 large, unblemished pink or red grapefruit, washed and dried
1 ½ cups granulated sugar
1 large egg
1 large egg yolk
1 ½ Tablespoons cornstarch
1 stick (1/2 cup) butter, melted and cooled slightly
Preheat oven to 325F with a rack positioned in the center. Place tart shells on a cookie sheet and set aside to prepare filling.
Using a sharp knife or vegetable peeler, carefully cut away the zest of the entire grapefruit, leaving the pith (thick white stuff) behind. Cut the zest into smallish pieces and put into the bowl of your food processor or blender.
Cut both ends from the grapefruit so that it is stable while standing on your cutting board. Using a sharp knife, cut the pith from the actual fruit in long slices from top to bottom, rotating the grapefruit about 15 degrees after each cut. Trim away any remaining pith.
Hold the grapefruit over the food processor and use a small, sharp knife, cut down alongside one membrane that divides the grapefruit sections. When you reach the bottom of the section, turn the knife upwards, following the section of grapefruit and come up the membrane on the other side. This ‘V’ shaped cut should cleanly release the segment of grapefruit. Repeat with each segment until you’re left with all the membranes. Squeeze the membrane over a strainer that is positioned above the food processor to get the rest of the juice from it. Make sure you’ve fished out any stray seeds before proceeding.
Add the sugar to the food processor, tighten the lid and process until smooth. Pour the sugar/grapefruit mixture into a bowl and whisk in the egg and the egg yolk. When that is thoroughly combined, whisk in the cornstarch and then the butter.
Pour immediately into tart crusts and place in oven. Bake for 16 minutes for individual tarts (or 20 minutes for a large tart.)
Raise heat to 350F. Continue baking for an additional 10-15 minutes (or 15-20 minutes for large tart.) Remove cookie sheet to a cooling rack and allow to cool for 20 minutes undisturbed. Remove tarts from pans and allow to cool to room temperature prior to serving. Store leftovers, tightly wrapped, in the fridge up to a week. Not that they’ll last that long, mind you…