Begin by peeling, coring, and dicing your apples into uniform ½-inch cubes. Toss them immediately with lemon juice in a large bowl to prevent browning.
In a large skillet over medium heat, melt the butter until it begins to foam slightly. Add the apples and cook for 2-3 minutes, stirring occasionally.
Sprinkle in the brown sugar, cinnamon, nutmeg, cardamom (if using), and salt. Continue cooking for 7-10 minutes, stirring occasionally, until the apples are tender but still maintain their shape.
While the apples cook, preheat your oven to 350°F (175°C). In a mixing bowl, combine the oats, flour, brown sugar, chopped nuts, cinnamon, and salt.
Using your fingertips or a pastry cutter, work the cold butter into the dry ingredients until you have a crumbly mixture with pea-sized butter pieces throughout.
Spread the topping mixture evenly on a parchment-lined baking sheet. Bake for 15-18 minutes, stirring halfway through, until golden brown and fragrant. Allow it to cool completely on the baking sheet.
In clear serving glasses or mason jars, create beautiful layers starting with 2-3 tablespoons of the cooled apple mixture.
Follow with a generous layer of vanilla Greek yogurt (about 2 tablespoons). Add a sprinkle of the crisp topping (about 1-2 tablespoons).
Repeat the layers until you reach the top of your glass, finishing with a final sprinkle of crisp topping.
For an extra touch of elegance, drizzle with a small amount of maple syrup or honey and garnish with a fresh mint leaf.