Place jam in a microwave-safe bowl and microwave on high for 30 seconds or until melted. Strain through a fine strainer, pushing on solid fruit with the back of a spoon until most of the liquid is extracted. Discard solids.

Combine strained jam, half and half, powdered sugar and strawberry extract in a medium size bowl. Stir until well combined. Add pink food coloring and stir well to combine. If icing seems a bit too thin, add a little more powdered sugar. If too thick, add more half and half.

Place icing in a freezer-strength, gallon-size zippered plastic bag. Snip a tiny snip off one lower corner of the bag and drizzle icing decoratively back and forth across cake. Scatter top and sides of cake with sprinkles, if desired. Allow to sit for at least one hour for icing to harden.