Bake the cake: Preheat the oven to 350°F (175°C). Prepare the cake mix according to the box instructions with water, oil, and eggs. Pour the batter into a greased 9x13-inch pan and bake for 28–32 minutes, or until a toothpick comes out clean.
Make the pineapple topping: While the cake bakes, heat the crushed pineapple (with juice) and 1 cup sugar in a saucepan over medium heat. Stir until the sugar dissolves and the mixture gently boils, then remove from heat.
Add the pineapple topping: Let the baked cake cool for 10–15 minutes. Poke holes all over the surface with a fork, then slowly pour the warm pineapple mixture evenly over the cake to soak in.
Make the frosting: Beat the softened butter and cream cheese together until smooth. Add vanilla extract, then gradually beat in the powdered sugar until fluffy.
Frost the cake: Once the cake is fully cooled, spread the cream cheese frosting across the top. Let some pineapple show through for a rustic, homemade look.
Finish and serve: Sprinkle chopped pecans generously over the frosting. Slice into squares and enjoy every sweet, tropical bite!