Rinse rosemary well and pat dry.

Combine strawberries, sugar, and lemon juice in a large pan.

Cook over medium-low heat, stirring frequently, until juice starts to release.

Gradually raise heat to high and boil hard for 20-30 minutes, scraping the bottom to prevent sticking.

Continue cooking until foam subsides and the mixture darkens.

Turn off heat and skim off any white foam.

Stir in Marsala, tasting as you go, until the flavor is present but not overpowering.

Return to medium heat and cook, stirring frequently, for 3-5 minutes, until glassy and dark.

Test for doneness by placing a small spoonful of jam on a frozen spoon and chilling for 1-2 minutes.

Tilt the spoon to see if the jam runs slowly and has thickened to a gloppy consistency. If watery, cook longer.

Remove from heat and skim any remaining foam.

Stir well to distribute berries and liquid evenly.

Place rosemary stalks into jam, stir, leave 1 minute, taste, and remove or leave to steep longer.

Pour into sterilized jars and store in the refrigerator for up to 4 weeks.