Heat the oven to 350ºF with a rack in the middle position.

Coat the bottom and sides of a 9-inch springform pan with cooking spray, then dust evenly with semolina flour, tapping out the excess.

In a food processor, combine ½ cup of the sugar and the lemon zest. Process until moist and fragrant, about 15 seconds.

Add the ricotta and mascarpone and process until smooth, about 30 seconds, scraping down the sides as needed. Add the semolina, egg yolks, Marsala, lemon juice and salt, then process until combined, about 10 seconds. Transfer to a large bowl.

In a stand mixer with a whisk attachment, whip the egg whites on medium-high until light and foamy.With the mixer running, slowly add the remaining ¼ cup of sugar and continue to whip until the whites hold soft peaks, 1 to 2 minutes.

Add a third of the egg whites to the cheese mixture and fold until combined. Add the remaining whites and fold until just incorporated.

Transfer to the prepared pan, spreading into an even layer and tapping on the counter to release any large air bubbles.

Bake until the top is lightly browned and the cake is just set but still jiggles when shaken, 40 to 45 minutes.

Let cool completely in the pan on a wire rack, about 2 hours. Cover and refrigerate for at least 2 hours.

Run a knife around the inside of the pan and remove the pan sides before slicing.