In a mixer bowl, hand-whisk water and yeast together and let stand 2 to 3 minutes to dissolve yeast. Briskly whisk in vanilla, sugar, eggs, softened butter, and salt and blend well. Add 3 to 4 cups bread flour and mix. Then knead with dough hook on lowest speed of mixer 6 to 8 minutes, adding more bread flour as necessary to form a soft, bouncy dough. (If you don’t have a stand mixer simply add flour until the dough is too stiff to stir by hand, then turn out onto a lightly floured surface and knead for about 8 minutes, adding flour as needed to prevent sticking. Your dough is ready when it’s smooth, soft and bounces back when you press your thumb into it.).
Remove dough hook and spray dough with nonstick cooking spray. Cover entire mixer and bowl with a large clear plastic bag (I used saran wrap to very loosely cover the bowl). Let dough rise 30 to 60 minutes or until almost doubled.
Turn out dough onto a lightly floured work surface and gently deflate. Cut dough into 12 equal portions. Shape each into a small round roll or bun. Place about 3 inches apart on prepared baking sheet. Whisk 2 eggs and a pinch of sugar together in a small bowl. Brush each bun well with egg wash.
Preheat oven to 350 degrees F.
For butter crumb topping, in a small bowl, rub ingredients together to form a crumbly mixture. Distribute carefully on top of each bun. Cover buns loosely with plastic wrap and let rise about 30 to 45 minutes or until quite puffy and almost doubled.
Bake for 28 to 35 minutes or until browned all over.