Combine the sugar and water in a medium saucepot over medium-high heat, stirring constantly until the sugar melts.

Once the mixture is liquid, allow it to cook over medium heat until it is amber in color. Allow the amber color to deepen a bit and when it looks like the color of caramel, stir in the butter. Be careful, as the mixture will spatter.

Once the butter is completely melted, remove the caramel from the heat and carefully stir in the heavy cream until the mixture is smooth. Set aside.

Preheat the oven to 375º.

Combine the apples, lemon juice and zest, caramel sauce, cinnamon, and salt in a large bowl. Toss to combine. Transfer to a buttered 8x8-inch baking dish and set aside while you make the topping.

In a mini food processor, pulse the oats with the walnuts until coarsely chopped. Combine in a bowl with the flour, sugar, baking powder, and salt. Mix well to combine.

Stir in the beaten egg until the mixture resembles coarse crumbs. Sprinkle the mixture over the apples and pour the melted butter overtop. Sprinkle the top with cinnamon.

Bake the apple crisp for 30-35 minutes, or until golden brown and then apples are tender. As soon as you take the apple crisp out of the oven, drizzle the top with caramel sauce.

Allow the apple crisp to cool completely and then cover and refrigerate. You can make this up to 3 days ahead and serve it cold, at room temperature, or warm! It’s delicious with ice cream or whipped cream for topping and additional caramel sauce, of course!