Preheat the oven to 375 degrees F. Roll the pie crust dough out into a large 11-inch circle, then lower it into a standard 9-inch deep dish pie pan. Crimp the edges of the pie crust, then line it with a piece of parchment paper. Place pie weights (or dried beans) in the parchment to fill out the pie crust and hold it in place. Bake the crust for 15 minutes. Carefully remove the parchment holding the pie weights and set the crust aside.
Meanwhile measure the flour into a large bowl. Slowly pour in the grapefruit juice, whisking to blend with the flour so no clumps form. Then whisk in 2/3 cup Wholesome!® Organic Blue Agave, eggs, evaporated milk, and a pinch of salt. Add 1-2 drops of red food coloring to enhance the color. Whisk well to incorporate and avoid red dots in the pie.
Carefully pour the mixture into the partially baked pie crust. Gently tap the pie on the counter to bring the bubbles to the surface. Then carefully place the pie in the oven, being careful not to slosh the filling.
Bake for 50-60 minutes, until the outside edges of the filling are set, but the interior is still just a little jiggly. If you notice the crust is starting to turn dark, lay a flat sheet of foil over the whole pie and continue baking. Cool the pie completely before proceeding, either on the counter top or in the refrigerator.
Once totally cool, whip cold heavy cream in the mixer with 3 tablespoons agave. Whip on high until firm peaks form, then scoop the whipped cream onto the top of the pie. Refrigerate until ready to serve. Garnish with fresh grapefruit slices right before serving if desired. Can be made 3 days ahead.