Combine warm water, 1 tbsp granulated sugar, and active dry yeast. Let sit for 5-10 minutes until foamy.

In a stand mixer, mix bread flour, salt, and remaining sugar. Add yeast mixture, beaten egg, melted butter, and vanilla extract. Knead for 5-7 minutes until smooth and elastic (the dough will be tacky).

Place in an oiled bowl, cover, and let rise in a warm spot for 1 to 1.5 hours until doubled.

Grease a 9x13 pan generously with softened butter. Gently stretch dough to fit the pan. Let rest if it resists.

Cover and let rise for another 45-60 minutes until puffed. Preheat oven to 400°F (200°C).

Dimple the dough deeply with oiled fingers. Fill each well generously with raspberry jam.

Bake for 20-25 minutes until golden brown.

While baking, whisk powdered sugar, milk, and vanilla extract to make a fluid glaze.

Let focaccia cool for 10 minutes, remove from pan to a rack, and pour glaze generously over the warm bread. Serve immediately.