Line a 9 × 5-inch loaf pan with two overlapping sheets of plastic wrap, leaving enough overhang to lift the cake out later.
Trim the brownie so it fits the bottom of the loaf pan, then press it firmly into place.
Spread the softened vanilla ice cream evenly over the brownie layer.
Freeze for about 2 hours or until the vanilla layer is firm.
Spread the softened strawberry ice cream evenly over the vanilla layer.
Gently fold or scatter the sliced fresh strawberries throughout the strawberry ice cream layer.
Freeze for at least 3 hours, or overnight, until the Easy Berry Ice Cream Cake is completely firm.
Lift the cake from the pan using the plastic wrap overhang.
Top with frozen mixed berries and garnish with fresh mint if desired.
Let the cake stand for 10 to 15 minutes before slicing and serving.