In a stand mixer, combine warm water with sugar, whisking until dissolved. Sprinkle in active dry yeast and let sit for 5 minutes until bubbly.

In a separate bowl, whisk together bread flour, all-purpose flour, and salt. Gradually add the dry mixture to the stand mixer and knead for about 5 minutes.

Coat a clean bowl with olive oil, transfer the dough into it, cover, and let rise in a warm place for about 1 hour until doubled in size.

Gently punch down the dough, transfer to a greased 9x13 inch pan, fold over itself a couple of times, cover, and let rise for another hour.

Preheat your oven to 425°F. Poke dimples all over the surface of the dough, spread raspberry jam evenly, and prepare for baking.

Bake for 18-22 minutes until golden brown and fragrant. The crust should be light with a soft interior.

Once removed from the oven, let cool for 10 minutes. Poke additional holes in the top and fill with more raspberry jam.

In a small bowl, mix powdered sugar with enough milk for a smooth consistency. Frost the top and bottom of the focaccia with the icing.

Cut into squares and serve warm or at room temperature, perfect for any meal or snack.