Preheat the oven to 375 F, and lightly spray with non-stick spray, or line with a piece of parchment paper.
Spread the chopped strawberries onto the baking sheet and sprinkle with the lemon juice and sugar. Roast for 30 minutes, until juicy, and the tips of the fruit are just starting to caramelize.
Scrape the hot, roasted strawberries into a saucepan. Over medium heat, bring the strawberries to a simmer. Cook the berries, stirring frequently, until the liquid has reduced to a syrupy consistency, and you have about 1 1/2 cups of fruit (pour it into a liquid measuring cup to check the volume). This might take about 15-20 minutes.
Use a blender or food processor to pulse the strawberries a few times until mostly smooth. Transfer the strawberries to a container and refrigerate until well chilled.
In a large bowl, whisk together the chilled strawberries with the sweetened condensed milk, vanilla extract and orange liqueur.
Separately, use an electric mixer to whip the cream until you have soft peaks. Fold 1/3 of the whipped cream into the strawberry/sweetened condensed milk mixture to loosen it up, then fold in the remaining whipped cream.
Spoon the ice cream into your ice cream container/s. Put the lid on your container and freeze until firm enough to scoop, about 6-8 hours.