• Preheat oven to 360 degrees F (182 C) and prepare your baking dish. I'm using a square 9" non-stick baking dish, ceramic coated, so no need to grease it.

Step 1. Make The Oat Crumble Topping First

• Place you butter in the freezer for at least 1 hour before starting. Then, if you’re doing it by hand, use a grater: in a bowl, rub the frozen butter against the smaller grating surface on a box grater. Toss the frozen shreds of butter with flour until all pieces are coated. Faster food processor method: add the cold butter and the flour to the bowl of a food processor and pulse the mixture until you have a chunky / crumb like mixture.
• To the butter and flour mixture, add the rest of ingredients and mix to combine with a spatula this time. Place the oat crumb topping in the fridge while you make the rest.

Step 2. Prepare the peach filling:

• Rinse the peaches and pat dry, cut into wedges. I do not peeled them and the peach crisp turned just fine!
• Add sliced peaches to the baking dish. Add lemon juice, maple sugar, flour, cinnamon and cardamom.
• Gently stir until coated. I'm using the same baking dish for mixing the ingredients. Spread the peach filling in an even layer.

Step 3. Assemble the peach crisp

• Sprinkle the crumbly oat topping over peaches. Bake in the oven for about 35 minutes, or until the topping is golden brown. 
• If using frozen peaches, the baking time could take 5 to 10 minutes longer. Use broiler function for the last 2-3 minutes for a golden crust.
• Once it’s crisp and golden remove from oven and let it cool. Serve warm, cold or room temperature.