Make the Sponge:
Preheat oven to 350°F (175°C). Grease and line a 9x13-inch baking pan with parchment paper.

In a stand mixer with whisk attachment (or using a hand mixer), beat eggs and sugar on high speed until tripled in volume, pale, and ribbon-like, about 8-10 minutes. The mixture should hold a trail for 3 seconds when whisk is lifted.

Gently fold in sifted flour in three additions, being careful not to deflate. Fold in vanilla and melted butter with final flour addition.

Pour into prepared pan and spread evenly. Bake 18-22 minutes until golden and springy to touch. Cool completely in pan, then turn out onto a cutting board.

Make the Caramel Sauce:
Combine sugar and water in a heavy-bottomed saucepan. Cook over medium-high heat without stirring until deep amber, 8-10 minutes. Swirl pan occasionally for even coloring.

Remove from heat. Carefully whisk in cream—mixture will bubble vigorously. Add butter, whisking until smooth.

Stir in salt and vanilla. Cool to room temperature. Reserve ¼ cup for finishing; the rest goes into the trifle layers.

Prepare the Stewed Apples:
Peel, core, and slice apples into ½-inch wedges.

Melt butter in a large skillet over medium heat. Add apples, brown sugar, cinnamon, nutmeg, and salt.

Cook, stirring occasionally, until apples are tender but still hold their shape, 12-15 minutes. They should be jammy at the edges but not mushy.

Add Calvados if using, cook 1 minute more. Cool completely—warm apples will melt the custard layers.

Make the Crème Anglaise:
Combine milk, cream, and vanilla bean (seeds and pod) in a medium saucepan. Heat over medium until steaming and just beginning to bubble at edges. Remove from heat, cover, and steep 15 minutes.

In a large bowl, whisk egg yolks and sugar until pale and slightly thickened, about 2 minutes. Add salt.

Remove vanilla pod from milk mixture. Slowly pour about ½ cup hot milk into yolks, whisking constantly to temper. Gradually add remaining milk, whisking continuously.

Return mixture to saucepan. Cook over medium-low heat, stirring constantly with a wooden spoon or silicone spatula, reaching all corners of the pan.

Cook until custard reaches 170-175°F (77-80°C) and thickly coats the back of a spoon. When you draw a finger through the coating, the line should hold without running back together. This takes 8-12 minutes—do not rush. If custard begins to steam heavily, reduce heat.

Immediately strain through a fine-mesh sieve into a clean bowl. Press plastic wrap directly onto surface to prevent skin. Refrigerate until completely cold and thickened, at least 2 hours.

Make the Whipped Cream:
Beat cold cream, powdered sugar, and vanilla until soft peaks form. Do not overbeat—cream should be billowy, not stiff. Refrigerate until assembly.

Assemble the Trifle:
Cut sponge into 1½-inch cubes or fingers that fit your trifle bowl.

Layer 1 (Bottom): Arrange a single layer of sponge pieces in the bottom of a 3-quart glass trifle bowl. Brush generously with Calvados or cider. Drizzle with 3 tablespoons caramel sauce.

Layer 2: Spoon half the stewed apples over sponge, spreading to edges of bowl so layers are visible through glass.

Layer 3: Pour half the crème anglaise over apples, spreading gently to cover completely and reach the edges. Let this set in the refrigerator 20-30 minutes before continuing.

Layer 4: Add another layer of Calvados-brushed sponge and caramel drizzle.

Layer 5: Add remaining stewed apples.

Layer 6: Pour remaining crème anglaise over apples. Refrigerate 30 minutes to set.

Layer 7 (Top): Spread or pipe whipped cream over the custard, creating swirls and peaks.

Refrigerate assembled trifle at least 2 hours, or overnight for best flavor melding.

To Finish:
Just before serving, drizzle reserved caramel sauce over whipped cream and scatter generously with chopped macadamia nuts.