Line an 8-1/2x4-1/2-inch loaf pan with plastic wrap, allowing some excess to hang over the sides.
Put the condensed milk, evaporated milk, and cream cheese in a blender and blend on low speed until smooth, about 2 minutes. Add the lime zest and blend briefly. With the blender running on medium-low speed, slowly pour the lime juice through the hole in the blender’s cap. Turn the blender off as soon as all of the juice is incorporated. (The juice will thicken the mixture; additional blending can thin it too much.)
Pour about one-third of the lime mixture into the loaf pan, spreading it evenly. Spoon half of the dulce de leche in a thick line down the length of the terrine to the left of center. (If it’s too thick to spoon, heat it in the microwave for 30 seconds.) Pour and spread another third of the lime filling on top. Spoon the remaining dulce de leche to the right of the center. Pour and spread the remaining lime filling on top. Sprinkle the crumbs evenly over the top, cover the pan with plastic wrap, and freeze for at least 8 hours.
Combine the blackberries, sugar, and liqueur in a 1-quart saucepan. Bring to a simmer over medium-low heat, stirring occasionally, until the berries release some of their juice but remain mostly whole, about 5 minutes. Let cool briefly, then cover and refrigerate until ready to serve.
Uncover and invert the terrine onto a cutting board. If the terrine doesn’t release, let it sit at room temperature for 5 minutes inverted, and then gently bang the cutting board on the counter to release. Carefully peel off the remaining plastic wrap. To serve, dip a knife into hot water and dry it before slicing the terrine into pieces 3/4 to 1 inch thick. Transfer the slices to serving plates and let sit for 5 minutes before serving so they are creamy, not icy. Spoon some of the sauce over each slice and serve.
Make Ahead Tips
The assembled terrine can be frozen for up to 1 month. Remove from the pan and garnish with the sauce just before serving.
nutrition information (per serving):
11, Fat Calories
100, Saturated Fat
8, Monounsaturated Fat
47, Polyunsaturated Fat
Photo: Scott Phillips