For filling: In a medium saucepan, whisk together eggs, lime juice, sugar, butter, zest, and food coloring if using until well combined. Cook over medium-low heat, whisking constantly, until thickened, 5 to 10 minutes. Strain mixture into a medium bowl, and cover with plastic wrap, pressing directly on surface to prevent a skin from forming. Refrigerate for 45 minutes.
Preheat oven to 350°. Spray a 13x9-inch baking pan with baking spray with flour.
Meanwhile, for cake: In a large bowl, beat cake mix, eggs, ¾ cup water, lime juice, oil, and gelatin with a mixer at medium speed until thick and smooth, 2 to 3 minutes, stopping to scrape bowl. Spread into prepared pan.
Bake until a wooden pick inserted in center comes out clean, 25 to 30 minutes. Let cool for 5 minutes. Using the handle of a wooden spoon, poke holes all over top of warm cake. Spread lime filling onto cake. Let cool completely.
In a large bowl, beat cream cheese with a mixer at medium speed until smooth creamy, about 3 minutes. In another large bowl, beat cream and zest with a mixer at medium speed until soft peaks form. Gradually add confectioners’ sugar, beating until stiff peaks form. Fold whipped cream into cream cheese until smooth. Spread onto cake. Cover and refrigerate for up to 3 days. Garnish with lime slices, if desired.
Recipe by Paula Deen Magazine at https://pauladeenmagazine.com/key-lime-poke-cake-recipe/