Preheat oven to 350°F (175°C). Line a 15x10-inch jelly roll pan with foil and spray with baking spray containing flour.

Beat eggs in a large bowl on high speed for about 5 minutes, until thick and pale yellow. Add cake mix, water, and oil. Beat on low speed for 30 seconds, then medium speed for 1 minute. Scrape down sides of the bowl as needed. Pour batter into the prepared pan.

Bake for 11-14 minutes, or until the cake springs back when lightly touched. Do not overbake. Remove from oven and carefully run a knife around the edges if the foil did not cover the entire cake.

Lay a clean kitchen towel on a flat surface and sprinkle evenly with 1 tablespoon of powdered sugar. Turn the hot cake upside down onto the towel and carefully remove the foil. While hot, roll the cake up tightly inside the towel, starting from a short end. Cool completely on a wire rack while rolled up, about 1 hour.

Make the caramel buttercream: Cream the softened butter and caramel sauce until combined and slightly chunky. Add the powdered sugar and vanilla extract, mixing until smooth and fluffy.

Make the chocolate ganache: Combine heavy whipping cream and chocolate chips in a microwave-safe bowl. Heat for 1 minute, then whisk until smooth. Heat for an additional 30 seconds if needed to melt all chips.

Once the cake is completely cooled, carefully unroll it. Spread the caramel buttercream evenly over the entire surface of the cake. Reroll the cake neatly.

Place the re-rolled cake on a wire rack set over a cookie sheet to catch drips. Drizzle the chocolate ganache evenly over the top of the cake roll. Immediately sprinkle with the toasted pecans.

Chill the cake loosely covered in the refrigerator for at least 30 minutes before slicing and serving. Store leftovers loosely covered in the refrigerator for up to 3 days.