Preheat your oven to 350°F. Prepare a 9-inch springform pan by cutting a piece of parchment paper to fit the bottom, spraying the pan with vegetable spray, and placing the parchment inside.

In a large food processor, combine the sugar and lemon zest. Pulse for about a minute until the lemon is fully integrated and fragrant.

Add the flour, baking powder, and salt to the sugar mixture. Secure the lid and cover the food processor with a dish towel to prevent flour from escaping. Pulse 5-6 times until well mixed.

Incorporate the diced butter into the mixture by pulsing about 20 times. Set aside one cup of this mixture for the crumb topping.

In a separate small bowl, whisk together the milk, egg, Greek yogurt, and vanilla until well combined.

Create a small well in the flour mixture and pour in the liquid ingredients. Pulse until just combined; the batter should be smooth.

Mix the walnuts, oats, and cinnamon into the reserved crumb mixture, tossing well to combine. Set this aside.

Spread half of the batter into the prepared pan, smoothing the top with a spatula. Layer the sliced strawberries on top, overlapping them if necessary.

Spoon the remaining batter over the strawberries and smooth it out with a spatula. Evenly sprinkle the crumb topping over the batter.

Bake in the preheated oven for 50 minutes to an hour, or until a toothpick inserted into the center comes out clean.

Once baked, allow the cake to cool to room temperature before removing the collar. To transfer the cake, gently lift an edge of the parchment paper and slide your fingers underneath to support the cake as you move it to a stand or platter.