Preheat oven to 350ºF (177ºC). Butter a 9X13 inch baking dish, or spray with nonstick cooking spray; set aside.
In a medium mixing bowl, whisk together, all-purpose flour (2 cups), strawberry-flavored Jell-O (2 tablespoons), salt(1/4 teaspoon), and baking powder (1 3/4 teaspoons) until evenly combined.
In the bowl of a stand-up mixer, set with the whisk attachment, add the room-temperature eggs (5) and cream of tartar (1/2 teaspoon). Beat on high for 1 minute. Gradually add the sugar (1 cup). Continue to beat on high for 8 minutes. Add vanilla (2 teaspoons) and beat until combined.
With the mixer on low, gradually add oil (1/2 cup), then mix well to combine.
Add milk (1/2 cup) and beat on medium for 2 minutes. Scrape down the sides of the bowl and mix batter until evenly combined.
With the mixer on low again, gradually mix in the flour mixture until it's just combined. If there are any bits of flour on the side of the bowl, fold in with a spatula. We don't want to overmix at this stage or the cake can become tough and dense.
Pour batter into prepared baking pan and bake for 18-20 minutes, or until a toothpick inserted into the center of the cake comes out clean.
In a large liquid measuring cup (I use a 4 cup) combine evaporated milk (1 can), sweetened condensed milk (1 can), and heavy cream (1/2 cup) mixing until evenly combined.
When the cake has completely cooled, pierce the top of the cake, all over with a fork or bamboo skewer.
Slowly pour the milk mixture over the top of the cake, making sure to pour near the edges and all around. Refrigerate the cake for at least 4 hours or, better, overnight, to allow it to soak up the milk.