Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.
In a large bowl, mix together the oatmeal, chopped almonds, dried cranberries, and lemon zest.
In a separate bowl, whisk the egg with the melted butter and vanillin until smooth.
Combine the wet ingredients with the dry ingredients and mix until everything is evenly coated and the mixture begins to stick together.
Scoop out small mounds (about 1.5 tablespoons) and place them on the prepared baking sheet. Flatten slightly if desired.
Bake for 12–15 minutes, or until the edges are golden and the cookies are firm to the touch.
Remove from the oven and let cool for 5 minutes on the tray before transferring to a wire rack to cool completely.