Preheat to 325°F. Grease and fully line two 7.75 × 3.75-inch loaf pans.
Whisk all dry ingredients.
Whisk sugars and wet ingredients until smooth.
Fold dry into wet just until combined; set aside.
Thaw peaches in a sieve 30-45 minutes; press out liquid. You should have 220-240 g drained.
Cook peaches with sugar, cornstarch, and salt 3-5 minutes until glossy and lightly thickened. Cool fully.
Mix flour, sugars, and salt for streusel.
Stir in melted butter until large damp clumps form.
Divide batter between pans (about one-third full each).
Add thick streusel layer; lightly press.
Spoon half the peaches per loaf.
Cover with remaining batter.
Finish with very generous streusel.
Bake 45 minutes, tent, bake 10–15 more until cake center reaches 205-210°F.
Cool 20 minutes in pans, then remove and cool completely.
Whisk powdered sugar, non-dairy milk, vanilla bean paste, and salt for glaze.
Drizzle glaze over loaves.
