Grate zucchini on the large holes of a box grater. Place in a clean kitchen towel and squeeze firmly to remove excess moisture. You want about 1 cup packed, dry grated zucchini. Set aside.

Preheat oven to 350F. Grease a 9x5 inch loaf pan and line with parchment paper, leaving an overhang for easy removal. In a large bowl, whisk together almond flour, erythritol, baking powder, and salt until no lumps remain.

In a separate bowl, whisk eggs until frothy, about 30 seconds. Add oil, lemon juice, lemon zest, and vanilla. Whisk until smooth.

Pour wet ingredients into dry ingredients. Stir with a rubber spatula until just combined. Fold in the squeezed zucchini. The batter will be thick but pourable.

Scrape batter into prepared pan and smooth the top. Bake 50-55 minutes, until the top is golden and a toothpick inserted in the center comes out clean. The loaf will spring back when lightly pressed. Cool in pan 15 minutes, then lift out using parchment and cool completely on a wire rack.

Whisk powdered erythritol with lemon juice until smooth and pourable, adding more juice by the teaspoon if needed. Drizzle over cooled loaf. Let set 10 minutes before slicing.