Place a strainer lined with paper towels over a bowl.Pour in the container of natural yogurt and let it drain for 4 hours in the refrigerator.Lemon curd: In a saucepan, combine the lemon juice, zest, and half of the sugar and bring to a boil.In a bowl, whisk together the eggs and remaining sugar.Gradually add the warm liquid to the eggs, whisking constantly.Return the mixture to the saucepan and place it over low heat.Whisk constantly until the mixture thickens and the first bubble appears.Remove from heat, transfer to a container with a high rim, and add the cubed butter.Emulsify the lemon cream with an immersion blender.Once all the butter is incorporated and the cream is smooth, strain it through a fine-mesh sieve or cheesecloth, cover with plastic wrap, and refrigerate for at least 8 hours.Homemade Granola: Preheat the oven to 350 F (180 C) and line a large baking sheet with a silicone mat. In a bowl, combine the rolled oats, wheat flakes, sliced almonds, and dried cranberries. Set aside.In a saucepan, combine the honey, oil, and vanilla and bring to a boil.Remove from heat, add the dry mixture, and stir until everything is well coated.Spread the mixture evenly onto the prepared baking sheet.Bake for 20 minutes, stirring occasionally with a fork.Remove from the oven and let cool on the baking sheet. Once the mixture is completely cool, store it in an airtight container.Assemble the parfaits: Divide the drained yogurt among glasses.Top with lemon curd and homemade granola.Refrigerate until serving.