In a large bowl, heat the milk until it is just warmer than room temperature–be sure it's not too hot. Mix in the maple syrup. Add the yeast and let it sit for 5-10 minutes until it "blooms" or activates and becomes bubbly/foamy. Whisk in the applesauce, avocado oil, and flaxseed meal. Once fully combined, fold in the white whole wheat flour and 1 ¾ c of the all-purpose flour. Cover the bowl and set aside in a warm place to rise for an hour. In the meantime, make the filling. For the chocolate filling, just mix the cane sugar, cocoa powder, and oil. For the strawberry filling, bring the strawberries, maple syrup and lemon juice to a boil then reduce to a simmer, until it reduces to the consistency of jam.
Once the dough is done rising it should be about double in size. Fold in another ½ c all-purpose flour, baking powder, and salt, then transfer to a floured surface. Use the remaining flour as needed (you may need more or less) to knead. Knead the dough for 5-10 minutes. Do NOT keep adding flour until the dough is dry; only add flour if it is really sticking to the counter/surface. Divide the dough in two.
Make sure the surface is well-floured so it doesn't stick, then roll each dough (make sure your rolling pin is floured too). Roll until it is about ½" thick. Cut off the edges to make them super clean. You can use the scraps to make more later. This is optional, but it will result in the best-looking rolls. Spread the filling evenly throughout (chocolate on one, strawberry on the other). For the strawberry filling, spread the oil on the dough before adding the "jam".
Prepare a sheet pan with parchment paper and set aside (you will need multiple rounds since they need room to spread). Preheat oven to 350 degrees Fahrenheit.
You can roll and cut the traditional way, but I find this method much easier and has a better-looking result: Cut the dough while it's flat, about 1" thick slices. Roll each slice individually and transfer to the prepared pan. Combine one chocolate roll with one strawberry and pinch the ends together. Form into the shape of a heart--you want to exaggerate the shape because it will spread when it bakes.
Bake for about 8 minutes. While they're baking, make icing with powdered sugar and a splash of plant milk. Serve warm with the icing or alone. If you aren't planning to finish them on the first or second day, freeze as soon as it cools, and microwave to reheat.