1. Preheat the oven to 400 degrees Fahrenheit. Lightly grease a 10-inch cast iron skillet and line the bottom with parchment paper.

2. Whisk together the flour, sugar, baking powder, and salt in a large mixing bowl.

3. In a glass measuring cup, whisk together the buttermilk, egg yolk, and vanilla until evenly combined.

4. Scatter the cold butter pieces over the flour mixture and rub them into the flour with your fingertips until distributed.

5. Create a well in the center of the flour mixture and pour in the buttermilk mixture.

6. Use a rubber spatula to mix until a moist, shaggy dough forms.

7. Transfer the dough to the prepared skillet and smooth it evenly in the pan.

8. Gently press the sliced strawberries into the surface.

9. Bake for 25 to 30 minutes, until golden brown and baked through.

10. Cool the shortcake for 10 minutes.

11. For the topping, stir together the quartered strawberries, sugar, and lemon zest in a medium bowl and let them macerate.

12. For the whipped cream, combine the heavy whipping cream, sugar, and vanilla in a chilled mixing bowl.

13. Beat with an electric mixer fitted with a whisk attachment on medium speed until soft peaks form.

14. Spoon the strawberries and juices over the shortcake and serve with whipped cream.