Step 1

Position your oven rack in the center and preheat to 400°F (200°C). Take a clean 9-inch square pan or tube pan and wipe it thoroughly with white vinegar, allowing it to dry completely. This removes any trace of grease that might prevent your meringue from rising properly.

Step 2

In a spotlessly clean large bowl, begin beating the room temperature egg whites on medium speed until they become foamy, about 1 minute. Add the cream of tartar and salt, then increase the mixer speed to medium-high. The cream of tartar stabilizes the egg whites, helping them maintain their structure.

Step 3

With the mixer running, gradually add the sugar, one tablespoon at a time, allowing 3-4 seconds between additions. This slow addition ensures the sugar dissolves completely. Once all sugar is incorporated, add the vanilla extract and continue beating until the meringue is stiff and glossy, about 5-7 minutes total. Test by rubbing a small amount between your fingers - it should feel completely smooth, not grainy.

Step 4

Using a large spatula, gently transfer the meringue to your prepared pan. Create a slight depression in the center by building the sides slightly higher than the middle. Place the pan in the preheated oven and immediately turn off the heat. Do not open the oven door for any reason - the residual heat will gradually bake your torte overnight.

Step 5

After at least 6 hours or the next morning, remove your torte from the oven. It should be crisp and lightly colored on the outside while remaining slightly soft in the center. Allow it to cool completely on a wire rack, about 30 minutes.

Step 6

When ready to serve, combine the cold heavy cream and powdered sugar in a chilled bowl. Beat until stiff peaks form, about 2-3 minutes. The cream should be firm enough to hold its shape but not overbeaten to the point of becoming grainy.

Step 7

Spread the whipped cream over the cooled torte, creating decorative swirls with the back of a spoon. Top with fresh berries, arranging them in a pleasing pattern. Serve immediately for the best texture and presentation.