Step 1

Stir milk, cream, butter, and salt in a large saucepan, then scrape in vanilla seeds; add pod. Bring to a simmer over medium heat, stirring occasionally, until mixture is warm and butter is melted.

Step 2

Meanwhile, whisk egg yolks and sugar in a medium bowl until very pale and light, about 3 minutes. Add cornstarch, whisking until no dry spots remain. Whisking constantly, gradually add warm milk mixture. Return mixture to saucepan and cook over medium-high heat, whisking constantly, until custard is thick and pudding-like in texture, and begins to boil, about 6 minutes.

Step 3

Strain custard through a fine-mesh sieve into a medium bowl, using a rubber spatula to help press it through. Cover with plastic, pressing directly onto surface, and chill until cold, at least 2 hours.

Step 4

Do Ahead: Custard can be made 3 days ahead. Keep chilled.

Step 5

Cook 1 lb. raspberries and ¾ cup sugar in a large saucepan over medium heat, stirring occasionally and skimming foam from surface, until thick and jammy, 6–8 minutes. Remove from heat and let sit 5 minutes. Transfer to a medium bowl and gently fold in remaining 1 lb. raspberries until coated, being careful not to break them up. Cover and chill until cold, about 2 hours.

Step 6

Using an electric mixer on high speed, beat cream, salt, and remaining 1 Tbsp. sugar in a large bowl until stiff peaks form. Cover and chill.

Step 7

Trim edges of 13x9" sponge cake to square off. Cut cake lengthwise into 5 strips about ⅛" thick; these will be placed inside the trifle bowl, flush against the glass, to create the appearance of an even and continuous band of cake for each layer. Cut or tear remaining cake into ½" pieces (you will need about 4 cups).

Step 8

Using an offset spatula, evenly spread ½ cup whipped cream into bottom of trifle bowl. Arrange a strip of cake inside bowl with cut side flush against the glass. Gently press cake into whipped cream to secure. Repeat with another strip of cake, trimming to fit, until cake strips touch at ends to make a continuous ring. Arrange about 2 cups cake pieces in a single layer over cream (and within cake band), pressing gently to secure.

Step 9

Brush 2 Tbsp. orange liqueur over cake layer. Spread half of raspberry compote over, then gently press down into cake layer. Place whole berries against the glass to create a ring of berries (check outside of bowl as you go). Using offset spatula, spread about 2 cups custard over raspberry layer. At this point, your trifle bowl should be a little less than half full. If filling is past that point, hold back a bit on next layers. (On the other hand, if Paul Hollywood is giving you side-eye and you want to win this thing, spoon out some custard to get back down to the midway mark.)

Step 10

Top custard layer with about 1½ cups whipped cream, spreading wall-to-wall in a thin, even layer. Repeat with remaining cake strips, cake pieces, orange liqueur, raspberry compote, and custard. Finally, top with whipped cream. The bowl should now be completely full with cream billowing over the top.

Step 11

Loosely cover trifle with plastic wrap and chill at least 5 hours and up to 12 (it will settle a bit as it chills).

Step 12

For a traditional look, swirl cream decoratively with offset spatula. For a modern presentation, place the dull edge of a knife or other flat-edged tool against top rim of bowl and scrape any excess cream off the edge. This will give you a flat layer of cream perfectly flush with top rim of bowl.

Step 13

If desired, pulverize dried raspberries in a blender on medium-high speed until very finely ground. Transfer to a fine-mesh sieve and dust over trifle until completely covered. Or, for a red disco finish, sprinkle luster dust over trifle, letting a little cream peek through here and there.

Step 14

Serve chilled.