Center a rack in the oven and preheat the oven to 400°F. Line a baking sheet with parchment or a silicone mat.
In a small bowl, stir the cream and egg together.
In a separate, larger bowl, whisk together the flour, sugar, baking powder and salt. Drop in the butter and, using your fingers, toss to coat the pieces of butter with flour. Quickly, working with your fingertips or a pastry blender, cut and rub the butter into the dry ingredients until the mixture is pebbly.
Pour the cream/egg mixture and 3/4 cup peaches over the dry ingredients and stir with a fork just until the dough, which will be wet and sticky, comes together. Don't overdo it. Still in the bowl, gently knead the dough by hand, or turn it with a rubber spatula 8 to 10 times.
Lightly dust a work surface with flour and turn out the dough. Divide it in half. Working with one piece at a time, pat the dough into a rough circle that's about 5 inches in diameter, cut it into 6 wedges and place it on the baking sheet. (At this point, the scones can be frozen on the baking sheet, then wrapped airtight. Don't defrost before baking- just add about 2 minutes to the baking time.)
Bake the scones for 20 to 22 minutes, or until their tops are golden and firm. Transfer them to a rack to cool completely (or you can eat them warm if you're not adding the glaze).
PREPARE THE GLAZE:
In a medium bowl, whisk together the glaze ingredients. Drizzle over the cooled scones. The glaze will eventually set at room temperature, or you can put the scones in the refrigerator for a few minutes to speed up the process.