In a small bowl, combine the Greek yogurt with honey and fresh lime zest, stirring until fully incorporated and smooth. This mixture will be your 'frosting' for decorating the watermelon tree. The honey adds subtle sweetness and the lime zest brings a bright, fresh flavor that complements the watermelon perfectly—I find this balance prevents the yogurt from tasting too plain.

Slice the watermelon quarter into 1-inch thick triangles, keeping the rind intact on the base for stability. Working with each triangle, carefully trim away most of the rind on the sides and top, leaving only the middle third as a 'trunk' at the bottom—this creates the tree silhouette and gives you a flat surface to pipe on. The triangular shape naturally mimics a Christmas tree, and keeping the rind on the base ensures each piece stands upright.

Transfer the yogurt mixture from Step 1 into a piping bag fitted with a small star or round tip. Pipe decorative patterns, lines, or dots across the pink flesh of each watermelon triangle, working from the top point downward to create a festive tree design. Once decorated, place all the watermelon trees on a parchment-lined baking sheet and freeze for at least 2-3 hours until the yogurt is completely firm and holds its shape—I like to freeze them overnight so the yogurt becomes almost ice cream-like and won't run off when served.