1Tbsporange liqueursuch as Grand Marnier (optional)
Preheat the oven to 400 degrees F and line a baking sheet with aluminum foil. Place the strawberries in a large bowl, and toss with ¼ cup of the sugar to coat evenly. Spread on the prepared baking sheet and roast for 15-20 minutes, stirring and gently flipping the strawberries every 5 minutes. Allow to cool briefly, then transfer the berries and roasting liquid back into the same bowl. Use an immersion blender to puree (a regular blender or food processor will also work).
In a large bowl, vigorously whisk together the egg yolks and remaining sugar.
Place the half-and-half, clotted cream and vanilla in a medium saucepan over medium-high heat. Gently stir the mixture a few times as it heats up to help the clotted cream melt into the other ingredients.
Once the cream is just simmering, turn the heat to low. Briefly re-whisk the yolks, then ladle in the cream while whisking. Carefully pour the mixture back into the saucepan, using a spatula to scrape everything out of the bowl. Over low heat, stir the mixture for several minutes until it thickens slightly and coats the back of the spatula. Stir in the pureed strawberry mixture, along with the orange liqueur, if using. (Note: adding some alcohol to ice cream improves its texture).
Pour the ice cream base into a clean container (I like to use a quart-sized liquid measuring cup), and press plastic film directly against the surface to prevent a skin from forming. Place in the refrigerator and chill until very cold.
Prepare in an ice cream machine according to manufacturer's instructions.