Prep. Pre-heat oven to 350ºF.
Prepare a 9 inches square baking pan lined with parchment paper. Leave a few inches with parchment overhang on the sides so you can easily remove the brownies later.
Melt the chocolate using the double boiler method. Heat up a medium saucepan with a few inches of water in it. When it starts to simmer, place a heatproof bowl over the top with olive oil (coconut oil or melted butter) and chocolate chips. Stir with a whisk or spatula constantly until about 70-80 percent of the chocolate chips are melted. Take the bowl off the pot and continue stirring until all the chips are melted and the texture smooth.
In a medium mixing bowl beat the eggs with an electric mixer for 2-3 minutes until bubbly.
Pour in the melted chocolate mixture and mix on low speed until smooth. Add vanilla and sugar. Mix on low.
In a separate mixing bowl add all the dry ingredients: flour, cornstarch, salt, cocoa powder. Whisk until just combined. Combine wet and dry ingredients, stir with a rubber spatula until smooth.
Pour half of the brownie batter into the pan. Even the batter out with a spatula as much as you can and top with oreo layer. Add another layer of brownie batter, even out and bake for 20-25 minutes. The center should still be relatively moist (if we want to achieve fudgy brownies, for cakey brownies bake time should be a couple minutes longer). Toothpick inserted into center should be slightly moist and with breadcrumbs but not dry which will mean you have overbaked the batter.
Let cool in the pan for 10 minutes, remove from the pan and transfer to wire rack to cool completely. Refrigerate for at least one hour.
Meanwhile make the Chocolate ganache glaze. Prepare a heatproof medium bowl with chocolate chips. Set aside. In a small saucepot place the heavy cream and take it to a gentle boil. Immediately pour over the chocolate chips and let sit for 1-2 minutes. Whisk the mixture until chips are melted and the texture is smooth. The ganache will be thick but still easily pourable. It will thicken later. Pour over the brownie batter, spread out evenly with a spatula. Arrange crushed oreos on top layer along with your favorite valentine sprinkles. Chill in the refrigerator for another hour or two. Upon removing the brownie bars from the fridge, on an even surface or a large cutting board cut the brownies with a sharp knife into 9 larger bars (do this while they are still cold!). This helps with even cutting and creates uniform pieces. Let come to room temperature and melt slightly. Enjoy with a scoop of vanilla ice cream for a glass or milk!