Cut the butter into small slices and add to the Ninja Foodi Cold & Hot Blender. Add 1 cup of the chocolate chips. Put the lid on the blender and select cook mode on high. Cook for 3 minutes, then pulse several times and turn the heat down to low. Scrape the sides if needed. Cook on low for 2 more minutes. Add in 1 tsp espresso powder. Pulse until smooth.
Add the salt and sugar, press the pulse button for about 5 seconds. Add the eggs, oil, and vanilla extract. Press the pulse button for about 5 seconds. Scrape down the sides. Make sure the batter is well incorporated, pulse again if needed.
Sift the flour and the cocoa powder before adding to the blender. Add the mixture in ¼-½ cup increments, pulse for about 5 seconds between each addition. Or you can use the low blend function. If there is remaining flour on top, use the tamper tool or a spatula to push it down into the blender. You may need to stir the batter to incorporate the last addition of flour/cocoa powder. Use the low blend setting to finishing combining the batter. Scrape down the sides.
Once all the flour/cocoa powder is incorporated, add in the remaining ¾ cup of chocolate chips and stir with a spatula.
Line a 11.5"X 9" with either parchment or a silpat. If using parchment paper, coat the bottom of the pan with butter or crisco before placing the parchment on the pan.
Pour the brownie batter into the prepared pan and place it on the rack in the oven. Set the bake function on 325°F for 35 minutes. Remove and let cool for at least 15 minutes.
Cut and serve!