Gently wrap a 10×5-inch loaf pan in plastic wrap, and place in freezer.

In the bowl of a stand mixer fitted with the whisk attachment, beat cold cream, sugar, vanilla, and salt at medium-high speed until medium-stiff peaks form, 4 to 6 minutes.

In a medium bowl, stir together sweetened condensed milk and custard powder. Fold in one-third of whipped cream mixture. Fold in remaining whipped cream mixture just until combined. Pour into prepared pan. Cover and freeze overnight.

Let stand at room temperature until slightly softened before serving, about 5 minutes.