Combine pears and 3 tablespoons sugar in a small bowl. Cover and chill overnight.
Heat milk and ginger in a medium saucepan just until bubbles begin to form around edges of the saucepan.
Whisk together egg yolks and 1-1/4 cups sugar in a large bowl; gradually whisk in the hot milk. Return all to saucepan. Cook and stir over medium heat until mixture just coats a metal spoon. Remove pan from heat. Quickly cool the custard by placing the saucepan in a sink of ice water for 1 to 2 minutes; stir constantly. Pour mixture through a strainer into a large bowl to remove ginger. Cover and chill in the refrigerator overnight.
Freeze mixture in a 4- or 5-quart ice cream freezer according to manufacturer's directions. Stir in pear mixture after ice cream has thickened. Ripen for 4 hours.