Preheat the oven to 375 degrees F.

In a large bowl, combine strawberries, rhubarb, 1/2 cup dark brown sugar, maple syrup, vanilla, and 1/4 cup of flour.

Pulse remaining flour, baking powder, baking soda, remaining brown sugar, and salt in a food processor until combined.

Add butter and pulse until crumbs form.

Transfer to a large bowl, add poppy seeds, and stir in 1 cup of heavy cream until just combined.

Butter an 11x7x2-inch pan.

Spread the fruit mixture evenly in the pan.

Drop the batter in large blobs over the fruit.

Bake for 45 minutes to 1 hour, or until bubbly and golden brown.

Cool for at least 30 minutes.

Whip remaining heavy cream with sugar to medium-stiff peaks.

Fold in chopped basil.

Serve the cobbler warm, topped with basil whipped cream.