MAKE THE MERINGUE LAYERS

1. Position two racks near the center of the oven and preheat the oven to 225°F. Using a cake pan or cardboard cake round as a guide, draw a 9-inch circle on each of two pieces of parchment paper. Turn each paper upside down and place it on a baking sheet.

2. In the bowl of an electric mixer, using the whisk attachment, beat the egg whites at medium speed until foamy. Add the salt and cream of tartar and beat at medium-high speed until soft peaks begin to form. Gradually add the sugar, about 1 tablespoon at a time, then increase the speed to high and beat the whites until stiff peaks form.

3. Scrape the meringue into a large 8-inch pastry bag fitted with a medium plain tip (such as Ateco #6). Starting at the center of one of the circles, pipe a spiral of meringue out the edges, filling the circle completely. (Or, if you prefer, scoop some of the meringue into the center of the circle and spread it over the circle with a small metal spatula.) Repeat to fill the other circle. Use the remaining meringue to pipe 1¼-inch-wide dollops onto the baking sheet; these can be eaten as cookies.

4. Bake the meringue layers for 1 hour, until lightly colored and dry to the touch. Turn the oven off and leave the meringues in the oven for at least another 2 hours, or overnight.

MAKE THE FILLING

5. Place the white chocolate and ½ cup of the heavy cream in the top of a double boiler over barely simmering water. Heat, stirring frequently, until the chocolate is melted and smooth. Remove the chocolate from the heat and let cool to room temperature.

6. In the bowl of an electric mixer, using the whisk attachment, beat the remaining 2 cups heavy cream with the orange zest at high speed until soft peaks form. Remove the bowl from the mixer stand. Whisk about ½ cup of the whipped cream into the cooled chocolate. Pour this mixture into the rest of the whipped cream and, using a rubber spatula, gently fold it in. Do not overmix, or the cream will become grainy. Use the filling immediately, or refrigerate for up to 2 hours.

ASSEMBLE THE CAKE

7. Place one of the meringue circles on a cardboard cake round or cake plate. Scoop about 2½ cups of the filling on top and spread it into an even layer, almost to the edges. Arrange a ring of strawberries, cut side down, around the edge of the round, with the pointed ends facing out. Continue making concentric rings of strawberries until the filling is covered. Place the other meringue round on top, smooth side up. Using a small offset metal spatula, spread a thin layer of filling over the meringue, covering it completely.

8. Scrape the remaining filling into a pastry bag fitted with a medium star tip (such as Ateco #6). Pipe 8 large rosettes around the edge of the top and one in the center. Top each rosette with a sliced strawberry. Refrigerate the cake for at least 30 minutes before serving.