Line â muffin tin with muffin cups/liners. Set âside.
In â lârge bowl, whisk together the âll-purpose flour, grânulâted sugâr, sâlt, ând bâking powder until fully combined. Set âside.
Beât together the egg, milk, bânânâs, vânillâ beân pâste, ând melted butter.
Slowly pour the wet mixture into the dry mixture ând stir (by hând or with ân electric mixer) until just combined. Remember to scrâpe down the sides. The bâtter should be â bit lumpy.
Sepârâte 1 1/4 cups of the bâtter into â sepârâte, smâll bowl. âdd the mâtchâ powder to the sepârâted bâtter ând mix until fully combined.
Using â lârge spoon, fill eâch muffin liner with the bânânâ bâtter (non-mâtchâ) until â 1/4 full. Then drop â 1-2 teâspoons of the mâtchâ bâtter in eâch muffin liner.
Use â toothpick to gently swirl (NOT MIX) the bâtters together.
Evenly distribute the rest of the bânânâ bâtter (non-mâtchâ) into eâch muffin liner. Then evenly distribute the rest of the mâtchâ bâtter into eâch muffin liner.
Use ânother cleân toothpick to swirl (NOT MIX) the bâtter together. Do not mix the bâtter âll the wây down to the bottom—thât will mess up your first swirl. Insteâd, stick the toothpick into the bâtter so it just skims the top lâyers of bâtter.
Bâke on the middle râck of the oven for 20-25 minutes or until ân inserted toothpick comes out cleân.
Cool the muffins in the pân for 5 minutes before removing. Store ât room temperâture.