Preheat your oven to 325°F (165°C) and lightly grease a 12-cup muffin tin.
In a large mixing bowl, combine the rolled oats, chopped pecans, and almond flour.
In a separate bowl, whisk together the melted coconut oil, maple syrup, cinnamon, salt, and vanilla extract until smooth. Pour this liquid mixture over the dry ingredients, ensuring everything gets evenly coated.
Divide the granola mixture among the prepared muffin cups (about 3 tablespoons per cup). Using the bottom of a small glass or measuring cup, press the mixture firmly against the bottom and up the sides of each cup, creating a well in the center.
Bake for 15-18 minutes until the edges turn golden brown. Remove from the oven and use the back of a spoon to gently re-press the centers while still warm. Allow the tart shells to cool completely in the muffin tin before removing.
While the tart shells cool, prepare your apple filling. Toss the diced apples with lemon juice in a bowl to prevent browning.
In a medium saucepan over medium heat, melt the coconut oil and add the maple syrup, cinnamon, nutmeg, and cloves.
Add the apples to the saucepan and cook for 7-10 minutes, stirring occasionally, until they soften but still maintain some texture.
Remove from heat, stir in the vanilla extract, and allow the mixture to cool completely.
Carefully remove the cooled granola tart shells from the muffin tin. If they're sticking, run a butter knife gently around the edges to loosen.
If using plain Greek yogurt, mix it with honey and vanilla in a bowl until smooth. For pre-flavored yogurt, you can use it directly.
Spoon about 2 tablespoons of yogurt into each tart shell, creating a smooth layer.
Top each tart with a generous spoonful of the cooled apple mixture.
Refrigerate the assembled tarts for at least 30 minutes before serving to allow the flavors to develop and the tarts to set properly.