Toss the sliced strawberries with the sugar in a bowl. Let sit at least 10 minutes until the juices release, stirring once or twice. Reserve a few slices for the top.

In a large chilled bowl, whip the heavy cream and vanilla on medium-high speed until soft peaks form, about 2 to 3 minutes.

In a glass trifle bowl, layer a third of the cake chunks, a third of the strawberries with syrup, and a third of the whipped cream. Repeat twice, ending with the whipped cream mounded on top. Swirl the cream with a spoon and garnish with the reserved strawberry slices. Serve immediately or chill 1 hour.