Thoroughly wash 3 pounds of peaches and 1 lemon (including the rind) under cool, running, drinkable water. Peel and dice peaches.
In a large deep cast-iron skillet, melt 2 tablespoons of unsalted butter. Once melted, turn off and remove from the stove top.
Mix in peaches, juice of the whole lemon, 2 tablespoons of honey, 2 tablespoons of brown sugar, 1 tablespoon of cornstarch, 1 teaspoon of vanilla extract, ½ teaspoon of ground cinnamon, ¼ teaspoon of ground cardamom and a pinch of kosher salt. Stir well; set aside.
In a medium mixing bowl, combine 1½ cups of gluten-free old fashioned oats, ½ cup of almond flour, ⅓ cup of sliced almonds, ⅓ cup of brown sugar, 1 teaspoon of ground cinnamon, ¼ teaspoon of ground cardamom and ¼ teaspoon of kosher salt.
Dice 8 tablespoons of cold unsalted butter into small cubes and add to dry mixture. Use your hands to blend the butter into the other topping ingredients, until only pea-size pieces of butter remain. Stir in 2 tablespoons of pasteurized plain whole milk Greek yogurt, mix until the crisp mixture is moistened throughout.
Dollop spoonfuls of the crisp mixture over the peach filling and use your fingers to break up the mixture until it is evenly distributed.
Bake for 25-30 minutes, or until the filling is bubbling around the edges and the top is lightly golden. Allow to cool for 5-10 minutes before serving. Serve with a dollop of pasteurized whole milk Greek yogurt, fresh whipped cream, or a scoop of vanilla ice cream. Eat up, Mama!